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PURE  FOODS 

THEIR  ADULTERATION,  NUTRITIVE 
VALUE,  AND  COST 


BY 

JOHN  C.  OLSEN,  A.M.,  Ph.D. 

PROFESSOR  OF  ANALYTICAL  CHEMISTRY  AT   THE   POLYTECHNIC  INSTITUTI 

OF  BROOKLYN,   NEW  YORK.     AUTHOR  OF  "QUANTITATIVE  CHEMICAL 

ANALYSIS."      EDITOR  OF   VAN   NOSTRAND'S 

"CHEMICAL  ANNUAL,"  ETC. 


GINN  AND  COMPANY 

BOSTON  •  NEW  YORK  •  CHICAGO  •  LONDON 


•  •    •     •  •     • 


^QoLt\A^^^s^8r 


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ENTERED    AT    STATIONERS'   HALL 


COPYRIGHT,  1911,  BY 
JOHN  C.  OLSEN 


ALL   RIGHTS   RESERVED 
814.2 


tgbe  fltftengnm  grt« 

GINN  AND  COMPANY  •  PRO- 
PRIETORS •  BOSTON  •  U.S.A. 


PREFACE 

This  volume  is  the  outgrowth  of  a  series  of  public 
lectures  on  foods,  which  have  been  given  by  the  author  for 
a  number  of  years.  The  interest  shown  by  audiences  of 
widely  different  character,  as  well  as  frequent  requests  for 
the  substance  of  the  lectures  in  printed  form,  has  led  to 
their  publication.  The  experimental  illustrations  which 
accompanied  the  lectures  are  given  in  the  form  of  a  series 
of  experiments  at  the  end  of  each  chapter.  Some  of  these 
experiments  are  so  simple  that  they  may  be  carried  out  with 
ordinary  household  utensils,  others  require  a  few  chemicals 
and  simple  appauatus  which  may  be  purchased  at  any  drug 
store.  Many  of  them  require  a  fairly  well-equipped  chem- 
ical laboratory,  while  others  have  been  included  which  can 
be  performed  only  by  those  who  have  considerable  chemical 
training  and  facilities  at  their  command.  Most  of  the  descrip- 
tive matter  can  be  understood  by  the  average  intelligent 
reader,  although  even  here  a  knowledge  of  chemistry  will 
enable  the  reader  to  comprehend  the  subject  much  more 
fully. 

It  is  the  hope  of  the  author  that  this  volume  will  be  of 
some  service  to  the  very  important  class  of  teachers  and 
students  who  are  studying  the  chemistry  of  foods  in  the 
classroom  and  laboratory.  It  is  hoped  that  the  subject  has 
been  presented  in  such  a  manner  as  to  stimulate  the  interest 
of  such  classes,  and  that  domestic-science  teachers  will  be 
able  to  explain  and  expand  the  necessarily  brief  expressions 

iii 


iv  PURE  FOODS 

of  the  text,  as  well  as  perform  such  experiments  as  are  be- 
yond the  ability  of  the  student.  The  author  also  hopes  that 
the  volume  will  be  of  service  to  the  growing  class  of  intelli- 
gent men  and  women  who  desire  to  obtain  some  knowledge 
of  the  composition  and  function  of  the  foods  which  they 
prepare,  sell,  or  consume. 

Of  the  great  need  of  a  wider  and  fuller  knowledge  of 
the  nature  and  functions  of  the  food  which  is  of  such  vital 
necessity  to  us,  the  author  has  the  keenest  realization.  In 
an  age  when  intelligence  and  knowledge  are  recognized  as 
essential  to  the  most  efficient  performance  of  even  very 
simple  tasks,  it  is  surprising  that  most  of  us  eat  what  we 
like,  with  very  little  thought  of  the  ultimate  result. 

The  steel  for  our  bridges  and  buildings  is  bought  and 
sold  on  the  chemist's  certificate  of  its  composition  to  the 
thousandths  of  per  cent.  Foods  are  manufactured  and  sold 
on  flavor  and  appearance,  utterly  regardless  of  composition 
or  food  value.  The  coal  for  our  engines  must  be  tested  and 
analyzed,  but  the  far  more  precious  human  organism  is  loaded 
with  a  heterogeneous  mixture  of  fuel  of  unknown  composi- 
tion. We  should  not  be  surprised  at  low  efficiency,  inability 
to  work,  sickness,  even  the  premature  death  of  an  organism 
which  is  given  so  little  intelligent  care.  When  an  intelligent, 
well-informed  public  demands  analyzed,  tested  foods,  they 
will  be  better  served  by  the  food  producer,  manufacturer, 
and  salesman ;  and  if  such  food  is  consumed  in  the  physio- 
logically proper  quantity  and  variety,  there  will  be  far  less 
inefficiency,  sickness,  and  mortality. 

The  author  does  not  claim  originality  for  any  appreciable 
portion  of  this  volume.  For  most  of  the  general  facts  and 
ideas  presented  he  is  indebted  to  the  large  army  of  mu- 
nicipal, state,  and  national  pure-food  workers,  who  have 
accumulated  so  much  valuable  information  on  this  subject. 


PREFACE  V 

The  coming  generations  will  reap  large  harvests  of  comfort 
and  well-being  from  their  quiet  but  effective  work. 

The  author  wishes  to  express  his  indebtedness  to  many 
of  these  workers  whom  it  has  been  his  good  fortune  to  know 
personally,  and  also  to  many  others  whom  he  knows  only 
through  their  publications.  Statements  made  with  reference 
to  the  actual  conditions  of  our  food  supply  are  generally 
based,  at  least  in  part,  on  the  author's  tests  of  foods  in  the 
course  of  his  consulting  practice  as  a  chemist,  and  on  the 
results  of  investigations  carried  out  to  ascertain  the  com- 
position of  the  foods  on  the  market.  He  need  hardly  say 
that  this  volume  was  not  written  to  meet  the  needs  of  the 
technical  chemist. 

The  author  takes  great  pleasure  in  expressing  his  obliga- 
tion to  Mr.  Albert  E.  Seeker,  of  the  United  States  Depart- 
ment of  Agriculture,  for  reading  the  entire  manuscript  and 
making  many  valuable  suggestions.  He  is  also  under  obliga- 
tions to  Mr.  H.  C.  Humphrey  of  the  Corn  Products  Refin- 
ing Company  for  reading  the  chapters  on  Carbohydrates 

and  Candy. 

J.  C.  OLSEN 
Brooklyn,  New  York 


CONTENTS 

CHAPTER  PAGE 

I.  What  is  Food? 1 

11.  What  is  Pure  Food? 18 

III.  Standard  Rations  and  the  Cost  of  Food    .  23 

IV.  Milk 33 

V.  Bacteria  in  Milk 43 

VI.  Fats  and  Oils 60 

VII.  Butter  and  its  Substitutes 71 

VIII.  Meats 78 

IX.  Carbohydrates 88 

X.  Candies 101 

XI.  Aniline  Dyes  and  Other  Food  Colors     .     .  122 

XII.  Preservation  of  Foods 127 

XIII.  Fruits,  Jams,  and  Jellies 141 

XIV.  Fresh  and  Canned  Vegetables 155 

XV.  Bread  and  the  Cereals 159 

XVI.  Leavening  Agents 165 

XVII.  Spices  and  Condimental  Foods 172 

XVIII.  Flavoring  Extracts      . 180 

Appendix 189 

Index  . 199 

vii 


PURE  FOODS 

CHAPTER  I 
WHAT  IS  FOOD? 

The  animal  instinct  known  as  appetite  has  for  ages 
answered  this  question.  As  man  developed  intelligence  he 
learned  to  avoid  eating  certain  plants  or  animals  which 
produced  illness  or  death,  even  though  they  tasted  good. 
Still  more  slowly  he  acquired  crude  and  often  erroneous 
notions  of  the  nutritive  value  of  the  wholesome  foods. 
Very  little  progress  has  been  made  until  recently  in  the 
attempt  to  regulate  the  amount  and  proportion  of  the  vari- 
ous foods  consumed.  Most  civilized  nations  have  gener- 
ally overcome  the  dietary  methods  by  which  primitive 
races  have  alternated  between  gluttonous  indulgence  when 
food  was  plenty  and  starvation  and  want  at  other  times. 
Only  the  very  wonderful  ability  of  the  human  system  to 
adapt  itself  to  great  extremes  in  the  kmd  and  amount  of 
food  consumed  has  enabled  man  to  retain  his  vigor  while 
eating  as  a  savage.  The  unsanitary  condition  of  the  food 
supply  has  resulted  in  the  introduction  into  the  human 
system  of  innumerable  disease  bacteria.  Under  these  con- 
ditions the  sacrifice  of  life  has  been  appalling,  especially 
among  the  immature,  aged,  and  sick. 

Composition  of  foods.  Rapid  strides  have  recently  been 
made  toward  attaining  a  scientific  answer  to  the  question 
as  to  what  constitutes  food.    The  chemist  has  analyzed  the 


2^  ^^^        '  PURE  FOODS 

various  organs  of  the  human  system  and  discovered  that 
they  are  in  the  main  composed  of  but  four  chemical  ele- 
ments; namely,  carbon,  hydrogen,  oxygen,  and  nitrogen. 
Substances  composed  mainly  of  these  four  elements  are 
called  organic  matter.  The  bones  and  teeth  consist  largely 
of  calcium,  phosphorus,  silicon,  and  oxygen,  while  the 
blood  contains  considerable  quantities  of  iron  and  common 
salt,  which  is  a  compound  of  sodium  and  chlorine.  These 
chemical  elements  as  a  group  are  called  mineral  matter.  As 
compounds  of  these  elements  are  constantly  leaving  the 
body,  it  is  evident  that  to  mamtain  the  body  weight  these 
elements  must  constitute  the  bulk  of  our  food,  which  must 
also  be  composed  of  such  compounds  of  these  elements  as 
can  be  readily  digested  and  assimilated.  There  are  four 
large  classes  of  chemical  compounds  which  have  been  found 
to  meet  these  requirements  and  to  constitute  the  bulk  of 
our  foods;  namely,  carbohydrates,  fats,  protein,  and 
mineral  matter. 

Carbohydrates  are  composed  of  carbon,  hydrogen,  and 
oxygen.  This  class  may  be  subdivided  into  cellulose, 
starch,  and  sugar.  Cellulose  is  a  very  insoluble  substance, 
and  is  the  main  constituent  of  wood  and  vegetable  fibers, 
such  as  cotton  and  linen.  It  is  not  suitable  for  food  on 
account  of  its  insolubility.  The  starches  are  also  very  in- 
soluble compounds.  They  constitute  a  large  part  of  most 
seeds  and  grains.  When  the  grain  sprouts,  the  starch  is 
rendered  soluble  so  that  it  can  be  dissolved  by  the  sap  and 
nourish  the  growing  plant.  If  the  grain  is  eaten  by  man,  a 
similar  transformation  takes  place  during  digestion,  render- 
ing it  possible  for  the  soluble  carbohydrate  produced  to 
dissolve  in  the  blood,  which  carries  it  to  all  parts  of  the 
system.  As  cellulose  cannot  be  rendered  soluble  in  this 
manner,  it  is  not  suitable  for  food. 


WHAT  IS  FOO.D  ?  '■  :  •-  >    ^^"  "'>  -  '  -  S 

Sugars.  When  starch  is  rendered  soluble  it  passes  sooner 
or  later  into  some  form  of  sugar.  About  two  hundred  differ- 
ent sugars  have  been  discovered  by  chemists.  Only  a  few  of 
these  are  present  in  any  large  quantity  in  ordinary  foods. 
Cane  sugar  is  the  most  common  of  these  and  is  most  highly 
prized  as  a  food  on  account  of  its  sweet  taste.  It  is  ex- 
tracted in  large  quantities  from  the  juice  of  the  sugar  cane, 
sugar  beet,  and  maple  tree.  When  starch  is  rendered  solu- 
ble it  passes  into  other  sugars  which  are  less  sweet,  such  as 
dextrose  and  maltose.  They  are  fully  as  nourishing  as 
cane  sugar  and  pass  into  the  blood  more  quickly  because 
cane  sugar  must  first  be  broken  up  into  two  simpler  sugars 
called  dextrose  and  levulose. 

Solubility  of  the  carbohydrates.  The  chief  difference, 
therefore,  between  these  three  classes  of  carbohydrates  is 
found  in  their  solubility.  This  property  is  of  fundamental 
importance  in  a  food.  The  body  cannot  be  nourished  by 
cellulose  because  the  juices  of  the  body  cannot  dissolve  it. 
Starch  can  be  rendered  soluble  and  can  therefore,  after 
digestion,  nourish  the  body,  while  the  sugars  are  almost 
instantly  taken  into  the  circulation,  giving  immediate  re- 
lief from  exhaustion.  These  three  classes  of  carbohydrates 
contain  the  same  three  chemical  elements  in  almost  exactly 
the  same  proportion  (carbon,  44.4  per  cent;  hydrogen,  6.2 
per  cent;  and  oxygen,  49.4  per  cent).  The  same  chemical 
formula  [(CgH^QOg)"^]  is  used  to  represent  cellulose,  starch, 
and  dextrin,  which  indicates  that  the  chemical  elements  are 
present  in  the  same  proportion  (C  represents  carbon,  H 
hydrogen,  and  O  oxygen).  The  formula  for  dextrose  (grape 
sugar)  and  levulose  is  CgH^2^6*  "^^^^  formula  differs  from 
that  of  starch  by  HgO.  As  HgO  is  also  the  formula  for 
water,  the  transformation  of  starch  into  dextrose  consists 
in  the  addition  of  water,  and  has  therefore  been  called 


4'  '   "  '  '• '    '••-••'•  :^UEE  FOODS 

hydrolysis  and  may  be  represented  by  the  following  chemical 

equation:  CeH^oO,  +  H,0  =  C,H,A- 

Cane  sugar,  as  well  as  maltose,  is  represented  by  the  for- 
mula C12H22O11,  and  also  differs  in  composition  from  starch 
by  the  elements  of  water,  as  is  seen  from  the  following 
equation :        3  (.fi.fi,  +  H,0  =  C,,H,,0„. 

The  fats  and  oils  constitute  another  of  the  four  large 
classes  of  foods.  These  substances  are  also  composed  of 
the  three  elements,  carbon  (about  76.5  per  cent),  hydrogen 
(about  11.9  per  cent),  and  oxygen  (about  11.5  per  cent). 
They  differ  from  the  carbohydrates  in  that  they  contain  a 
much  smaller  proportion  of  oxygen.  They  are  also  more 
complex  in  structure,  being  composed  of  glycerin  combined 
with  fatty  acids.  When  fats  become  rancid  these  acids  are 
liberated,  giving  disagreeable  odors  and  tastes. ^  During  the 
process  of  digestion  the  glycerm  is  separated  from  the  fatty 
acids.  After  absorption  by  the  blood  these  constituents 
are  again  united  to  form  the  characteristic  fats  of  the 
human  system.  A  small  portion  of  the  fat  is  divided  into 
very  minute  globules  which  will  remain  suspended  in  the 
digestive  fluids,  producing  a  liquid  similar  to  milk.  The 
animal  fats  are  so  similar  to  each  other  and  to  vegetable 
fats  that  the  lard  from  hogs  fed  on  cottonseed  meal  will 
give  a  test  for  cottonseed  oil,  indicating  that  at  least  a 
portion  of  this  oil  has  been  deposited  unchanged  in  the 
tissues  of  the  animal. 

The  proteins  constitute  the  third  large  class  of  foods. 
They  contain  the  same  three  elements  as  the  two  precedmg 

1  The  presence  of  free  acid  alone  does  not  constitute  rancidity  (some  acid  oils 
not  being  rancid),  but  a  rancid  condition  is  the  result  of  complex  changes 
effected  by  the  action  of  light  and  air  on  oils,  causing  at  the  same  time  the  for- 
mation of  free  acid,  so  that  all  rancid  oils  are  acid,  but  not  all  acid  oils  are  rancid. 


WHAT  IS  FOOD?  5 

classes,  but  in  addition  contain  considerable  quantities  of 
nitrogen  (about  16  per  cent)  as  well  as  small  quantities  of 
sulphur  and  phosphorus.  Examples  of  this  class  of  foods 
are  the  lean  portions  of  meat,  the  white  of  eggs,  and  the 
gluten  of  wheat.  The  proteins  are  of  importance  in  the 
human  diet  almost  solely  on  account  of  their  content  of 
nitrogen.  As  the  living  cells  of  the  body  cannot  be  built 
up  or  nourished  on  any  other  food  but  proteins,  it  is  evident 
that  this  class  of  foods  is  of  vital  necessity  to  the  human 
system.  Fats  and  carbohydrates  can,  to  a  certain  extent, 
replace  each  other  in  the  human  diet,  but  neither  of  these 
can  replace  protein  matter ;  neither  can  the  human  system 
assimilate  nitrogen  in  any  other  form  than  protein.  Most 
proteins  are  readily  dissolved  by  the  gastric  juice  of  the 
stomach  and  the  digestive  fluids  of  the  intestines.  During 
this  process  the  proteins  are  broken  down  into  a  simpler 
class  of  nitrogenous  compounds  called  peptones.  The  pep- 
tones differ  from  the  proteins  in  that  they  are  more  soluble  ; 
for  instance,  a  protein  such  as  white  of  egg  is  precipitated 
by  boiling,  while  a  peptone  would  not  be  affected  by  this 
treatment. 

Mineral  matter  which  constitutes  the  fourth  class  of  foods 
is  present  in  small  amount  in  almost  all  portions  of  animals 
and  vegetables  which  are  used  as  food.  When  foods  of 
this  kind  are  burned,  the  carbon,  hydrogen,  oxygen,  and 
nitrogen  pass  off  as  gases,  while  the  mineral  matter  remains 
as  a  solid  and  is  known  as  the  ash.  The  amount  of  ash  ob- 
tained from  a  given  food  is  a  measure  of  the  amount  of 
mineral  matter  present.  If  the  ash  were  eaten,  only  a  small 
portion  would  dissolve  and  be  available  for  nourishing  the 
system.  The  mineral  constituents  are  in  such  a  form  of 
combination  in  animal  and  vegetable  matter  that  they  can 
be  dissolved  by  the  blood  and  deposited  in  the  bones  or 


6  PUEE  FOODS 

teeth  where  needed.  Most  natural  waters  contain  a  small 
but  appreciable  amount  of  mineral  matter  which  is  already 
in  solution,  ready  for  absorption.  If  present  in  unusual 
amount,  the  water  is  used  expressly  for  its  mineral  content 
and  is  called  a  mineral  water. 

It  is  evident,  therefore,  that  a  food  must  consist  of  readily 
soluble  compounds  containing  the  same  chemical  elements  which 
are  found  in  the  human  system. 

Food  as  a  source  of  energy.  While  food  is  utilized  to 
build  up  the  various  organs  of  the  human  system  and  repair 
waste,  it  must  also  serve  some  very  different  purpose  be- 
cause such  large  quantities  are  digested  and  taken  into 
the  circulation  and  then  expelled  again.  ^  Investigation 
shows  that  the  chemical  elements  do  not  pass  out  in  the 
same  form  of  combination  in  which  they  enter  the  system. 
The  greatest  difference  is  found  in  the  amount  of  oxygen 
in  combination  with  the  carbon  and  hydrogen.  These  ele- 
ments enter  the  system  combined  with  very  little  oxygen, 
and  pass  out  in  combination  with  the  maximum  quantity 
for  these  elements ;  that  is,  as  carbon  dioxide  and  water.^ 
It  has  been  demonstrated  that  this  oxygen  is  taken  from 
the  air  which  enters  the  lungs.  Whenever  carbon  or  hydro- 
gen combine  with  oxygen  a  large  amount  of  heat  is  evolved. 
When  food  is  oxidized  in  the  human  system  this  heat  is 
liberated  and  is  utilized  for  maintaining  the  normal  tem- 
perature of  the  body.  Heat  can  also  be  transformed  into 
other  forms  of  energy.  The  steam  engine,  for  instance, 
transforms  the  heat  obtained  by  burning  the  coal  into  me- 
chanical energy,  which  moves  trains  or  does  other  useful 
work.    In  the  same  way  the  energy  obtained  from  the  food 

1  A  child  in  growing  to  manhood  consumes  from  15  to  20  tons  of  food. 

2  Hydrogen  forms  a  higher  oxygen  compound  than  water  (HgO),  but  this 
compound  (hydrogen  peroxide,  H2O2)  cannot  exist  in  contact  with  animal 
tissues. 


WHAT  IS  FOOD?  7 

is  used  in  the  body  to  perform  muscular  work,  and  to  keep 
up  the  circulation  of  the  blood  and  other  activities  of  the 
various  organs.  The  system  requires  in  the  aggregate  a 
very  large  amount  of  energy  for  its  various  activities,  all  of 
which  is  obtained  from  the  food.  We  may  therefore  define 
food  as  follows : 

Food  must  consist  of  readily  soluble  compounds  containing 
the  same  chemical  elements  which  are  found  in  the  human 
system^  and  a  considerable  amount  of  energy  which  can  be 
liberated  by  oxidation. 

Functions  of  food.  It  is  evident,  therefore,  that  the  food 
serves  two  functions  in  the  animal  body.  It  serves  as  the 
material  from  which  the  animal  structure  is  built,  and  it 
also  furnishes  the  energy  to  keep  up  the  bodily  activities 
and  temperature,  the  greater  part  of  the  food  being  used 
for  the  latter  purpose  only.  The  marvelous  economy  of 
nature  is  shown  in  the  fact  that  when  any  portion  of  the 
animal  structure  is  worn  out  and  is  ready  to  be  discarded, 
it  is  first  decomposed  in  such  a  way  that  its  available  energy 
is  first  utilized  by  the  system.  Every  particle  of  food,  there- 
fore, which  is  dissolved  by  the  blood  gives  up  its  energy 
before  it  is  again  eliminated.  The  energy  content  of  the 
food  is  therefore  the  simplest  criterion  of  its  value.  That 
the  taking  of  food  gives  strength  and  energy  to  the  human 
system  is  a  matter  of  everyday  experience.  Scientific  inves- 
tigation has  shown  how  the  energy  value  of  a  given  food 
can  be  accurately  measured. 

The  calorie.  As  all  forms  of  energy  can  be  transformed 
into  each  other,  it  is  only  necessary  to  measure  the  energy 
given  out  by  a  food  in  one  of  these  forms.  The  heat  evolved 
when  the  food  is  burned  can  be  readily  measured.  For  this 
purpose  the  heat  is  absorbed  by  water  and  the  increase  in  tem- 
perature noted.    It  is  evident  that  with  unequal  quantities 


8  PURE  FOODS 

of  heat  the  same  amount  of  water  will  be  raised  to  the 
highest  temperature  by  the  largest  amount  of  heat.  In  other 
words,  the  temperature  to  which  a  given  quantity  of  water 
is  raised  will  be  a  measure  of  the  amount  of  heat  evolved. 
The  quantity  of  water  used  is  one  kilogram,  which  at  ordi- 
nary temperatures  is  very  nearly  equal  to  one  liter,  or  1.05668 
quarts.  The  Centigrade  scale  is  used  for  measuring  the  rise 
in  temperature.  The  amount  of  heat  necessary  to  raise  one 
liter  of  water  one  degree  Centigrade  is  called  a  Calorie. 

The  calorimeter.  For  determining  the  energy  value  of 
foods,  a  weighed  quantity  of  the  food  is  placed  in  a  hermet- 
ically sealed  bomb,  which  is  filled  with  oxygen  under  pres- 
sure. The  bomb  is  immersed  in  two  liters  of  water,  the 
temperature  of  which  is  taken  by  means  of  an  accurate  ther- 
mometer. A  platinum  wire  in  contact  with  the  food  is  then 
fused  by  means  of  an  electric  current  so  as  to  ignite  the 
food  which  burns  in  the  oxygen  surrounding  it.  The  heat 
is  absorbed  by  the  water,  which  is  kept  in  constant  motion 
by  means  of  a  stirring  device.  The  highest  temperature 
reached  by  the  thermometer  is  carefully  noted  and  the 
number  of  Calories  evolved  is  calculated,  a  correction  being 
introduced  for  the  heat  retained  by  the  bomb  and  the  vessel 
holding  the  water.  During  the  experiment  the  vessel  con- 
taining the  water  and  the  bomb  is  protected  from  loss  or 
absorption  of  heat  by  insulating  covers.  The  energy  value 
obtained  in  this  manner  is  called  the  calorific  value  of  the 
food.    The  instrument  used  is  called  a  calorimeter. 

1  Using  an  ordinary  (Fahrenheit)  thermometer,  a  Calorie  would  be  very  nearly 
equal  to  the  heat  necessary  to  raise  the  temperature  of  one  quart  of  water  two 
degrees.  A  much  smaller  unit,  known  as  the  small  calorie,  is  also  in  use.  It  is 
the  amount  of  heat  necessary  to  raise  the  temperature  of  one  cubic  centimeter 
of  water  one  degree  Centigrade.  A  liter  contains  1000  ccm.  (In  order  to  dis- 
tinguish these  units  from  each  other,  the  large  Calorie  is  spelled  with  a  capital 
C  and  the  small  calorie  with  a  small  letter.  The  calorific  value  of  foods  is 
generally  given  in  large  Calories.) 


Fig.  1.   Atwater-Mahler  Bomb  Calorimeter 

A,  bomb  immersed  in  water;  B,  cover;  C,  screw-cap;  G,  screw  connection 
for  attaching  to  oxygen  tank ;  H,  I,  wires  for  conducting  the  electric  current 
for  ignition  of  food  placed  in  platinum  cup  ;  KK,  ball-bearings  of  hard  steel 
to  avoid  friction  in  screwing  cup  down ;  L,  stirring  device ;  JV,  0,  insulating 
vessels  to  prevent  loss  of  heat ;  P,  thermometer 
9 


10  PURE  FOODS 

The  calculation  of  calorific  value.  As  the  calorific  value 
of  the  protein  (5.7),  fats  (9.3),  and  carbohydrates  (4.1) 
has  been  carefully  determined,  the  calorific  value  of  a 
given  food  may  be  calculated  if  its  chemical  composition 
has  been  determined.  In  making  such  a  calculation  the 
value  found  for  protein  in  the  calorimeter  is  not  used, 
because  this  constituent  of  foods  is  not  completely  oxi- 
dized in  the  human  system.  The  value  4.1  is  therefore 
used,  which  represents  the  amount  of  heat  evolved  in 
the  body.  The  following  values  are  therefore  used  in 
calculating  the  calorific  value  of  a  food: 

Protein 4.1  large  calories  per  gram 

Carbohydrates 4.1  large  calories  per  gram 

Fats 9.3  large  calories  per  gram 

It  is  evident  from  this  table  that  we  obtain  the  greatest 
amount  of  heat  and  energy  from  fatty  foods,  but  because 
such  foods  are  not  easily  digested  by  most  people,  carbo- 
hydrates are  generally  consumed  in  large  enough  quantities 
to  furnish  a  great  deal  of  the  requisite  amount  of  energy. 
By  far  the  most  common  carbohydrate  is  starch,  so  that 
starchy  foods  constitute  the  bulk  of  our  diet.  Because 
protein  matter  is  not  completely  oxidized,  it  cannot  serve 
economically  as  a  source  of  energy,  and  as  the  elimination 
of  its  decomposition  products  from  the  system  by  the  liver 
and  kidneys  involves  considerable  effort,  producing  dis- 
orders of  various  kinds,  it  should  not  be  consumed  in 
quantities  greater  than  necessary  to  keep  the  tissues  of 
the  body  in  good  condition.  The  statement  that  olive 
oil  has  a  calorific  value  of  4220  means  that  when  one 
pound  of  the  oil  is  burned,  4220  calories  of  heat  are 
liberated.  The  calorific  value  of  sirloin  steak  is  only 
1130   because  it  contains  62   per   cent  of   water,  which 


WHAT  IS  FOOD? 


11 


gives  no  energy  to  the  system,  its  function  in  a  food 
being  simply  to  hold  soluble  matter  in  solution,  rendering 
digestion  more  easy. 

Composition  of  foods.  It  is  evident  that  the  essential 
characteristics  of  a  food  can  be  indicated  by  giving  the 
percentage  of  water,  mineral  matter,  fat,  carbohydrates, 
and  protein  present,  as  well  as  the  calorific  value.  The 
following  table  gives  this  data  for  the  edible  portion  of  a 
number  of  common  articles  of  food.  The  foods  are  in  the 
raw  state  unless  otherwise  designated. 


TABLE  I 
Composition  and  Calorific  Value  of  Common  Foods 


Food  as  purchased 

Refuse 

Water 

Protein 

Fat 

Carbo- 
hydrates 

Mineral 
matter 

Calorific 
value 

Beef 

Per 

cent 

Per 
cent 

Per 

cent 

Per 

cent 

Per 

cent 

Per 

cent 

Calories 

Corned  

8.4 

49.2 

14.3 

23.8 

4.6 

1245 

Porter-house  steak     .    . 

12.7 

52.4 

19.1 

17.9 

0.8 

1100 

Sirloin  steak 

12.8 

54.0 

16.5 

16.1 

0.9 

975 

Round  steak 

7.2 

60.7 

19.0 

12.8 

1.0 

890 

Kibs 

20.8 

43.8 

13.9 

21.2 

0.7 

1135 

Rump 

20.7 

45.0 

13.8 

20.2 

0.7 

1090 

Lamb 

Leg,  hind 

17.4 

52.9 

15.9 

13.6 

0.9 

860 

Mutton 

Leg,  hind 

18.4 

51.2 

15.1 

14.7 

0.8 

890 

Loin  chops 

16.0 

42.0 

13.5 

28.3 

0.7 

1415 

Pork 

Bacon,  smoked  .... 

7.7 

17.4 

9.1 

62.2 

4.1 

2715 

Ham,  fresh 

10.7 

48.0 

13.5 

25.9 

0.8 

1320 

smoked     .... 

13.6 

34.8 

14.2 

33.4 

4.2 

1635 

Loin  chops 

19.7 

41.8 

13.4 

24.2 

0.8 

1245 

Salt  pork 

7.9 

1.9 

86.2 

3.9 

3555 

Tenderloin 

66.5 

18.9 

13.0 

1.0 

895 

12 


PUEE  FOODS 


TABLE  I  (Continued) 
Composition  and  Calorific  Value  of  Common  Foods 


Food  as  purchased 


Veal 

Breast 

Leg 

Leg  cutlets 

Poultry 

Chicken,  broilers  .    .    . 

Turkey 

Fish 

Cod,  fresh,  dressed    .    . 

salt 

Halibut,  steak  or  sections 

Lobsters 

Mackerel,  whole  .  .  . 
Oysters,  "  solids  "  .  .  . 
Perch,  yellow,  dressed  . 
Salmon,  canned     .    .    . 

Shad,  whole 

JEggs  and  Dairy  Products 

Butter 

Cheese,  full  cream     .    . 
skim  milk      ,    . 

Cream 

Eggs,  white 

yolk 

whole 

Milk,  whole 

skimmed  .... 

butter 

condensed    .    .    . 
Cereals 

Barley 

pearled   .... 
Buckwheat  flour    ,    .    . 


Refuse 


Per 

cent 

21.3 

14.2 

3.4 

41.6 

22.7 

29.9 
24.9 
17.7 
61.7 
44.7 

35.1 

50.1 


11.2 


Water 


Per 

cent 

52.0 
60.1 
68.3 


43.7 
42.4 

58.5 
40.2 
61.9 
30.7 
40.4 
88.3 
50.7 
63.5 
35.2 

11.0 
34.2 
45.9 
74.0 
86.3 
50.0 
65.5 
87.1 
90.5 
91.0 
26.9 

11.9 
11.3 
13.6 


Protein 


Per 

cent 

15.4 
15.5 
20.1 

12.8 
16.1 

11.1 
16.0 
15.3 

5.9 
10.2 

6.0 
12.8 
21.8 

9.4 

1.0 

25.9 

31.5 

2.5 

12.8 

16.0 

13.1 

3.2 

3.4 

3.0 

8.8 

10.3 
8.4 
6.4 


Fat 


Per 

cent 

11.0 
7.9 
7.5 

1.4 
18.4 

0.2 
0.4 
4.4 
0.7 
4.2 
1.3 
0.7 
12.1 
4.8 

85.0 

33.7 

16.5 

18.5 

0.4 

33.0 

9.3 

4.0 

0.3 

0.5 

8.3 

2.0 
1.0 
1.2 


Carbo- 
hydrates 


Mineral 
matter 


Per 
cent 


0.2 
3.3 


2.4 
2.0 
4.5 


5.0 

5.1 

4.8 

54.1 

73.3 

78.3 
77.9 


Per 
cent 

0.8 

0.9 

1.0 

0.7 

0.8 

0.8 
18.5 
0.9 
0.8 
0.7 
1.1 
0.9 
2.6 
0.7 

3.0 
3.8 
4.1 
0.5 
0.5 
1.0 
0.9 
0.7 
0.7 
0.7 
1.9 

2.5 
1.0 
0.9 


WHAT  IS  FOOD? 


13 


TABLE  I  (Continued) 
Composition  and  Calorific  Value  of  Common  Foods 


Food  as  purchased 

Refuse 

Water 

Protein 

Fat 

Carbo- 
hydrates 

Mineral 
matter 

Calorific 
value 

Cereals  (Continued) 

Per 

cent 

Per 

cent 

Per 

cent 

Per 
cent 

Per 
cent 

Per 

cent 

Calories 

Corn  meal 

12.5 

9.2 

1.9 

75.4 

1.0 

1635 

Graham  flour 

11.3 
10.3 

13.3 
13.4 

2.2 
0.9 

71.4 
74.1 

1.8 
1.3 

1645 

Macaroni,  vermicelli, etc 

1645 

Oatmeal 

7.7 
12.3 

16.7 
8.0 

7.3 
0.3 

66.2 
79.0 

2.1 
0.4 

1800 

Rice 

1620 

Rye  flour 

12.9 

6.8 

0.9 

78.7 

0.7 

1620 

Wheat  flour,  patent 

roller  process 

high  grade  and  med. 

12.0 

11.4 

1.0 

75.1 

0.5 

1635 

low  grade    .... 

12.0 

14.0 

1.9 

71.2 

0.9 

1640 

whole  wheat   .    .    . 

11.4 

13.8 

1.9 

71.9 

1.0 

1650 

Bread  and  Pastry 

Bread,  brown     .... 

43.6 

5.4 

1.8 

47.1 

2.1 

1040 

graham  .    . 

35.7 

8.9 

1.8 

52.1 

1.5 

1195 

rye      .    .    . 

35.7 

9.0 

0.6 

53.2 

1.5 

1170 

white  .    .    . 

35.3 

9.2 

1.3 

53.1 

1.1 

1200 

whole  wheat 

38.4 

9.7 

0.9 

49.7 

1.3 

1130 

Cake 

19.9 

6.3. 

9.0 

63.3 

1.5 

1630 

Oyster  crackers     . 

4.8 

11.3 

10.5 

70.5 

2.9 

1910 

Soda  crackers    .    . 

5.9 

9.8 

9.1 

73.1 

2.1 

1875 

Vegetables 

Beans,  baked     .... 

68.9 

6.9 

2.5 

19.6 

2.1 

555 

dried 

12.6 

22.5 

1.8 

59.6 

3.5 

1520 

Lima,  shelled.    . 

68.5 

7.1 

0.7 

22.0 

1.7 

540 

string 

7.0 

83.0 

2.1 

0.3 

6.9 

0.7 

170 

Beets  .    .    .    ....    .    . 

20.0 

70.0 

1.3 

0.1 

7.7 

0.9 

160 

Cabbage     

15.0 

77.7 

1.4 

0.2 

4.8 

0.9 

115 

Celery 

20.0 

75.6 

0.9 

0.1 

2.6 

0.8 

65 

Corn,  sweet,  green,  edi- 

ble portion  .    . 

75.4 

3.1 

1.1 

19.7 

0.7 

440 

canned      .... 

76.1 

2.8 

1.2 

19.0 

0.9 

430 

14 


PUKE  FOODS 


TABLE  I  (Concluded) 
Composition  and  Calorific  Value  of  Common  Foods 


Food  as  purchased 

Refuse 

Water 

Protein 

Fat 

Carbo- 
hydrates 

Mineral 
matter 

Calorific 
value 

Vegetables  {Continued) 

Per 
cent 

Per 
cent 

Per 

cent 

Per 

cent 

Per 
cent 

Per 
cent 

Calories 

Cucumbers 

15.0 

.81.1 

0.7 

0.2 

2.6 

0.4 

65 

Lettuce  .    . 

15.0 

80.5 

1.0 

0.2 

2.5 

0.8 

65 

Mushrooms 

, 

88.1 

3.5 

0.4 

6.8 

1.2 

185 

Muskmelons 

50.0 

44.8 

0.3 

4.6 

0.3 

80 

Onions    .    . 

. 

10.0 

78.9 

1.4 

0.3 

8.9 

0.5 

190 

Parsnips     . 

. 

20.0 

66.4 

1.3 

0.4 

10.8 

1.1 

230 

Peas,  dried 

, 

9.5 

24.6 

1.0 

62.0 

2.9 

1565 

shelled 

. 

74.6 

7.0 

0.5 

16.9 

1.0 

440 

green,  canned 

85.3 

3.6 

0.2 

9.8 

1.1 

235 

Potatoes,  Irish   .    . 

20.0 

62.6 

1.8 

0.1 

14.7 

0.8 

295 

sweet 

20.0 

55.2 

1.4 

0.6 

21.9 

0.9 

440 

Spinach 

92.3 

2.1 

0.3 

3.2 

2.1 

95 

Squash 

50.0 

44.2 

0.7 

0.2 

4.5 

0.4 

100 

Succotash,  canned 

75.9 

3.6 

1.0 

18.6 

0.9 

425 

Tomatoes   .... 

94.3 

0.9 

0.4 

3.9 

0.5 

100 

canned    . 

94.0 

1.2 

0.2 

4.0 

0.6 

95 

Turnips 

30.0 

62.7 

0.9 

0.1 

5.7 

0.6 

120 

Watermelons     .    . 

59.4 

37.5 

0.2 

0.1 

2.7 

0.1 

50 

Fruits 

Apples 

25.0 

63.3 

0.3 

0.3 

10.8 

0.3 

190 

Apples,  dried 

28.1 

1.6 

2.2 

66.1 

2.0 

1185 

Apricots,  dried 

29.4 

4.7 

1.0 

62.5 

2.4 

1125 

Bananas     .    . 

35.0 

48.9 

0.8 

0.4 

14.3 

0.6 

260 

Dates,  dried 

10.0 

13.8 

1.9 

2.5 

70.6 

1.2 

1275 

Figs,  dried 

18.8 

4.3 

0.3 

74.2 

2.4 

1280 

Grapes   .    . 

25.0 

58.0 

1.0 

1.2 

14.4 

0.4 

295 

Lemons  .    . 

30.0 

62.5 

0.7 

0.5 

5.9 

0.4 

125 

Oranges .    . 

27.0 

63.4 

0.6 

0.1 

8.5 

0.4 

150 

Pears      .    . 

10.0 

76.0 

0.5 

0.4 

12.7 

0.4 

230 

Raisins  .    . 

10.0 

13.1 

2.3 

3.0 

68.5 

3.1 

1265 

Raspberries 

85.8 

1.0 

12.6 

0.6 

220 

Strawberries 

5.0 

85.9 

0.9 

0.6 

7.0 

0.6 

150 

WHAT  IS  FOOD? 


15 


EXPERIMENTS 


1.  Starch  test.  Place  a  gram  or  two  of  starch  in  a  beaker  or  por- 
celain mortar,  add  a  little  water,  and  stir  so  as  to  make  a  thin  paste. 
Stir  the  starch  paste,  while  pouring  on  it  100  ccm.  of  boiling  water. 
Dilute  the  solution  with  an  equal  volume  of  water.  Place  a  few 
cubic  centimeters  of  the  starch  solution  in  a  beaker  or  test  tube  and 
add  a  few  drops  of  iodine  solution.^  The  blue  color  produced  is  a 
very  delicate  test  for  starch.  Various  articles  of  food  may  be  tested 
in  this  manner  for  starch,  such  as  flour,  potatoes,  vegetables,  etc.  The 
test  may  sometimes  be  obtained  without  boiling  with  water. 

2.  Test  for  reducing  sugar.  Prepare  Fehling's  solution  as  follows  : 
I.  Dissolve  7  gm.  (about  ^  oz.)  of  crystallized  sulphate  of  copper  in 
100  ccm.  of  water  and  place  in  a  bottle.  II.  Dis- 
solve 34.6  gm.  of  crystallized  Rochelle  salt  in 
45  ccm.  of  water,  also  25  gm.  of  caustic  soda 
in  40  ccm.  of  water.  Mix  these  two  solutions, 
dilute  to  100  ccm.,  and  preserve  in  a  bottle 
properly  labeled.  Equal  portions  of  solutions 
I  and  II  are  mixed  when  required  for  making 
a  test. 

Test  various  food  products  for  sugar  by 
means  of  Fehling's  solution.  Honey,  sirup, 
grape  juice,  or  other  fruit  juices  may  be  used. 
Dissolve  a  few  drops  of  these  foods  in  water, 
heat  to  boiling  in  a  beaker  or  other  suitable 
vessel,  and  add  a  few  drops  of  the  mixed 
Fehling's  solution.  A  bright  red  precipitate 
indicates  reducing  sugars,  such  as  dextrose, 
levulose,  etc.  Cane  sugar  does  not  give  this 
test  unless  it  is  first  boiled  with  acid. 

3.  Test  for  fatty  acids.  Add  a  few  drops  of  phenolphthalein^  to 
50  ccm.  of  alcohol  in  a  small  bottle  or  flask.  Add  a  diluted  solution  of 
caustic  soda  drop  by  drop  until  the  alcohol  is  colored  red.  Introduce 
a  few  cubic  centimeters  of  olive  oil,  butter,  lard,  or  other  fat  and 
shake  vigorously.    If  the  fat  or  oil  is  at  all  rancid,  the  red  color 


Fig.  2.  Tripod  and 
Wire  Gauze  arranged 
for  boiling  Liquids 
with  the  Bunsen 
Burner 


1  The  method  of  preparing  this  and  other  reagents  will  be  found  in  the 
Appendix,  page  189. 

2  One  tenth  a:ram  of  the  solid  dissolved  in  100  ccm.  of  alcohol. 


16  PURE  FOODS 

will  gradually  fade  because  the  alkali  is  neutralized  by  the  free 
fatty  acids. 

4.  Test  for  organic  nitrogen.  Introduce  a  small  portion  of  dry  meat, 
wheat  flour,  white  of  egg,  or  other  nitrogenous  food  into  a  test  tube. 
Add  a  piece  of  metallic  sodium  ^  or  magnesium  about  the  size  of  a 
pea.  Heat  to  redness  in  the  flame  of  a  Bunsen  burner.  When  cool 
dissolve  the  contents  of  the  test  tube  in  water  and  add  a  few  drops 
of  solutions  of  ferric  chloride  and  ferrous  sulphate  and  then  add 
hydrochloric  acid  until  the  solution  is  acid.  A  deep  blue  color  in- 
dicates the  presence  of  nitrogen  in  the  food  tested. 

5.  Test  for  mineral  matter.  Place  several  grams  of  flour,  potato, 
or  other  food  in  its  natural  state  in  a  platinum  or  porcelain  dish  and 
heat  over  a  Bunsen  burner  until  the  food  begins  to  burn.  The  black 
color  is  evidence  of  the  presence  of  carbon.  Continue  the  heating 
until  only  a  white  residue  remains.  This  is  the  ash  of  the  food  and 
contains  the  mineral  matter  of  the  food.  Add  a  little  water  and 
warm  and  moisten  a  piece  of  red  litmus  paper  with  the  solution. 
A  blue  color  indicates  the  presence  of  sodium  or  potassium  carbonate 
or  other  salts,  which  are  generally  present  in  considerable  quantities 
in  vegetables.  The  ash  may  also  be  tested  for  magnesium,  calcium, 
iron,  and  aluminum,  which  are  usually  present  in  vegetables. 

6.  Digestion  of  protein.  To  9  ccm.  of  dilute  hydrochloric  acid  add 
291  ccm.  of  distilled  water.  Dissolve  J^-  gm.  of  pepsin  in  150  ccm. 
of  the  diluted  acid.  Boil  a  fresh  egg  for  fifteen  minutes.  Remove 
the  white,  press  it  through  a  fine  sieve,  and  place  10  gm.  in  a  bottle 
of  suitable  size.  Add  35  ccm.  of  the  diluted  acid  and  rub  the  albu- 
men fine  with  a  glass  rod.  Add  5  ccm.  of  the  pepsin  solution. 
Cork  the  bottle  and  place  in  water  kept  at  52°  C.  (126°  F.).  Allow  to 
remain  for  several  hours,  shaking  occasionally.  The  albumen  has  now 
been  converted  into  peptone,  as  may  be  shown  by  the  following  tests. 
Boil  a  portion  of  the  solution  and  to  another  portion  add  zinc  sul- 
phate. Repeat  these  tests  with  a  solution  of  the  uncooked  white  of 
egg  in  water  and  observe  the  difference.  Peptone  may  be  precipitated 
by  the  addition  of  a  solution  of  tannin. 

7.  Test  for  solids  and  mineral  matter  of  milk.  Place  10  ccm.  of 
milk  in  a  porcelain  dish.  Evaporate  to  dryness  on  the  water  bath. 
Only  the  water  passes  off  during  the  evaporation.     The  residue 

1  Metallic  sodium  must  not  be  allowed  to  come  into  contact  with  water,  as 
it  may  explode.  It  should  be  kept  under  kerosene. 


WHAT  IS  FOOD?  17 

constitutes  the  solids  of  the  milk,  which  give  it  its  food  value.  Heat 
the  dish  with  the  Bunsen  burner  until  the  milk  solids  begin  to  burn. 
If  the  operation  were  carried  out  in  a  calorimeter  so  that  the  heat 
produced  would  pass  into  the  water,  the  calorific  value  of  the  milk 
would  be  obtained.  Continue  the  heating  until  the  solids  are  com- 
pletely burned  and  only  a  nearly  white  ash  remains.  This  ash  may 
be  tested  as  directed  in  the  preceding  experiment. 


CHAPTER   II 

WHAT   IS   PURE   FOOD? 

Pure  food.  The  term  ''  pure  food  "  can  be  defined  only 
after  long  experience  with  all  kinds  of  foods  and  very  ex- 
haustive scientific  and  practical  investigation.  While  much 
work  of  this  kind  has  been  completed,  many  investigations 
are  being  carried  on  at  the  present  time  in  order  to  deter- 
mine which  foods  are  pure  and  which  are  impure.  Food 
producers  and  manufacturers  have  by  no  means  arrived 
at  fixed  standards  of  excellence  for  their  products.  Many 
new  foods  are  being  constantly  placed  on  the  market,  in 
regard  to  which  no  reliable  opinion  can  be  given  until  they 
have  been  thoroughly  tested.  From  the  consumer's  stand- 
point there  is  such  a  great  difference  in  individual  consti- 
tution and  condition  that  Avhat  is  perfectly  harmless  and 
even  beneficial  to  one  man  may  be  poisonous  to  another. 
Our  present  definitions  of  a  pure  food  must  therefore  be 
tentative  and  subject  to  change,  as  time  goes  on,  to  meet 
the  requirements  of  experience,  scientific  investigation,  and 
the  changing  conditions  of  our  food  supply  and  manufac- 
ture. Many  foods  must  be  classed  as  pure,  even  though 
they  are  injurious  to  some  people. 

Adulterated  foods.  In  general  it  must,  of  course,  be 
assumed  that  a  pure  food  is  one  which,  properly  consumed, 
will  nourish  a  healthy  human  being  without  producing  dis- 
tress of  any  kind,  sickness,  or  death.  The  definition  of  a 
pure  food  indicates  the  method  of  differentiating  between 
foods  possessing  these  qualities  and  injurious  ones.    Foods 

18 


WHAT  IS  PURE  FOOD?  19 

are  also  classed  as  adulterated  if  the  purchaser  is  deceived 
as  to  their  natural  origin  or  constituents,  or  if  they  are 
below  standard  in  nutritive  value.  Such  standards  are 
fixed  by  law,  and  an  otherwise  pure  and  wholesome  food 
which  does  not  conform  to  such  standards  is  classed  as 
adulterated.  The  following  essentials  of  a  pure  food  have 
been  embodied  in  most  legal  definitions. 

Long-used  foods,  pure.  In  the  first  place,  a  food  is  pure 
if  it  has  been  in  common  use  for  a  long  time.  While  such 
a  food  may  be  injurious  under  certain  circumstances*,  and 
indeed  frequently  is,  it  is  not  called  impure  because  its 
peculiarities  are  a  matter  of  common  knowledge.  There  is 
no  deception  or  fraud  involved  in  the  sale  of  such  an  article. 
If  a  person  is  injured  by  eating  it,  it  is  held  to  be  his  own 
fault  in  that  he  is  ignorant  of  its  properties.  For  example, 
many  people  have  died  from  the  excessive  consumption  of 
pickles  and  vinegar.  Excessive  quantities  of  salt  are  inju- 
rious, so  that  the  eating  of  much  salt  meat  leads  to  serious 
disorders.  Although  sugar  is  one  of  the  best  foods  we  have, 
its  excessive  consumption  is  injurious.  No  one  would  think 
of  calling  these  well-known  foods  impure.  Any  attempt 
to  restrict  their  sale  or  consumption  would  certainly  fail. 

Substitution.  The  attitude  of  the  public  toward  a  new 
food  product  is  entirely  different.  If  it  can  be  shown  to  be 
injurious  toward  even  a  very  small  proportion  of  those  who 
eat  it,  it  is  apt  to  be  declared  unwholesome.  This  is  mainly 
due  to  the  fact  that  the  public  have  not  learned  by  long 
experience  just  what  the  circumstances  are  under  which  it 
is  injurious.  Opposition  to  a  new  food  is  especially  violent 
when  it  is  sold  under  the  name  of  a  common,  long-used 
food  or  mixed  with  such  a  food  product.  Such  a  practice 
constitutes  a  moral  as  well  as  a  legal  fraud.  A  food  sold 
in  this  manner  is  called  an  impure  or  adulterated  food,  even 


20  PUEE  FOODS 

though  it  may  be  entirely  harmless  and  nutritious.  It  is 
being  generally  recognized  that  Such  a  practice  is  poor 
policy  from  a  business  standpoint.  Many  examples  of  this 
kind  of  adulteration  may  be  cited.  Cottonseed  oil  has  been 
largely  sold  as  olive  oil.  A  large  number  of  the  sirups  on 
the  market  are  composed  in  large  part  of  glucose.  The 
best  California  wines  have  been  sent  to  France,  placed  in 
bottles  bearing  the  labels  of  well-known  French  brands  of 
wine,  and  returned  to  this  country.  The  inferior  California 
wines  have  been  sold  under  their  own  names.  The  Cali- 
fornia wine  grower  now  finds  that  his  product  has  a  bad 
reputation,  even  though  he  produces  wine  equal  to  any 
grown  in  France.  In  the  same  manner,  glucose,  although 
an  excellent  food  product,  is  generally  considered  injurious 
simply  because  it  has  always  been  sold  fraudulently,  and 
the  public  has  not  had  the  opportunity  to  use  it  knowingly 
and  learn  its  merits.  Many  people  have  long  used  cotton- 
seed oil  under  the  name  of  olive  oil  and  prefer  it  to  the 
real  article,  but  not  under  the  name  cottonseed  oil. 

Poisonous  constituents.  Every  food  is,  of  course,  con- 
sidered impure  and  adulterated  if  it  contains  constituents 
which  may  correctly  be  classed  as  poisonous,  such  as  arsenic, 
lead,  copper,  etc.  A  number  of  chemical  compounds  have 
been  used  as  preservatives  which  are  certainly  poisonous, 
while  a  few  preservatives  have  been  discovered  which  do 
not  seem  to  have  any  deleterious  influence  on  the  human 
system  when  consumed  in  small  quantities.  The  same 
statement  can  be  made  of  the  aniline  dyes.  Some  of  these 
brilliant  coal-tar  colors  are  highly  poisonous,  while  others 
have  been  fed  to  animals  in  large  quantities  and  even  in- 
jected directly  into  the  blood  without  any  ill  effect.  No  ill 
effect  has  been  observed  when  these  dyes  have  been  con- 
sumed in  large  quantities  by  human  beings.    Foods  which 


WHAT  IS  PURE  FOOD?  21 

have  been  derived  from  diseased  or  decayed  plants  or  ani- 
mals are  classed  as  impure  or  adulterated.  Such  foods  may 
contain  the  germs  of  disease  as  well  as  many  poisonous 
substances  which  are  known  to  be  produced  during  diseases 
or  in  the  process  of  decay.  Even  if  such  foods  do  not  con- 
tain any  poisonous  constituents,  everybody  has  such  a  strong 
natural  aversion  to  diseased  or  decayed  matter  that  the 
sale  of  such  food  is  violently  resented  by  the  public.  That 
partially  decayed  food  is  not  necessarily  injurious  is  evident 
from  the  large  consumption  of  the  so-called  fermented  cheese 
and  tainted  venison  and  other  meat. 

Reduction  of  food  value.  In  addition  to  the  requirement 
that  pure  foods  shall  contain  none  of  the  classes  of  poison- 
ous ingredients  already  named,  a  pure  food  is  defined  as 
one  from  which  none  of  the  nutritious  constituents  have 
been  withdrawn  or  the  food  value  lowered  in  any  manner. 
For  instance,  milk  from  which  the  cream  has  been  removed 
is  classed  as  adulterated  unless  it  is  sold  as  skim  milk. 
The  addition  of  water  is  also  a  fraud. 

Deception.  Pure  food  must  not  be  coated,  colored,  or 
pamted  so  as  to  appear  better  than  it  really  is.  For  instance, 
milk  is  sometimes  colored  to  make  a  poor  product  appear 
richer  in  cream.  Cheap  candies  are  often  coated  with 
shellac  varnish  so  as  to  imitate  the  appearance  of  choco- 
late, which  they  really  do  not  contain.  Both  of  these 
practices  are  condemned  as  fraudulent.  The  same  is  true 
of  the  addition  of  coloring  matter  to  butter;  while  this 
practice  is  illegal,  it  is  not  suppressed  because  most  people 
prefer  yellow  butter,  and  no  fraud  is  involved  unless  oleo- 
margarine is  colored  to  imitate  butter  and  is  sold  as  such. 

Misleading  labels.  By  legal  enactment  in  many  states, 
a  food  to  be  classed  as  pure  must  be  sold  under  a  name  or 
label  which  correctly  gives  its  composition  or  the  place  or 


22  PURE  FOODS 

firm  by  whom  it  is  produced.  To  prove  that  there  was 
nothing  injurious  in  its  composition  would  not  save  a  mer- 
chant from  prosecution  for  selhng  a  food  under  a  misleading 
label.  The  sale  would  be  fraudulent  because  the  purchaser 
would  be  getting  something  different  from  what  he  sup- 
posed he  was  getting  for  his  money. 

Legal  standards.  In  general,  a  food  to  be  called  pure 
must  conform  in  every  particular  to  the  law.  In  some  cases 
the  words  ''  pure  "  and  "  impure  "  or  "  adulterated  "  acquire 
a  very  unusual  meaning  by  legal  enactment.  For  instance, 
the  laws  of  many  states  specify  that  milk  must  contain  12  per 
cent  of  solids.  Some  cows  give  milk  containing  a  smaller 
proportion  of  solids.  The  sale  of  such  milk  is  illegal,  even 
if  it  is  shown  to  have  been  sold  in  absolutely  the  same  con- 
dition in  which  it  came  from  the  cow.  This  is  an  example 
of  an  absolutely  pure  natural  product  declared  by  law  to 
be  impure  and  adulterated.  Of  course  the  standard  fixed 
by  law  is  slightly  lower  than  the  average  composition  of 
pure  cow's  milk. 

Adulterated  food.  Food  is  impure  or  adulterated,  there- 
fore, when  it  contains  injurious  constituents  of  any  kind, 
when  it  is  below  the  standard  in  food  value,  when  sold 
under  some  form  of  fraud  or  deception,  or  when  it  does 
not  conform  m  some  respect  to  pure-food  laws.  The  words 
"  impure "  and  "  adulterated "  as  applied  to  foods  very 
rarely  imply  the  presence  of  what  are  commonly  considered 
poisonous  constituents. 


CHAPTER  III 

STANDARD  RATIONS  AND  THE  COST  OF  FOOD 

The  daily  ration.  If  the  amount  of  the  various  kinds  of 
food  consumed  during  twenty-four  hours  by  a  human  being 
under  normal  conditions  is  weighed,  and  the  total  amount 
of  each  of  the  food  constituents  is  calculated,  the  result 
gives  what  is  known  as  the  daily  ration.  For  a  given  age 
or  condition  of  life  this  is  found  to  be  surprisingly  constant, 
not  only  with  respect  to  the  total  amount  of  food  taken,  but 
also  with  reference  to  the  relative  amounts  of  fats,  car- 
bohydrates, and  protein.  The  total  calorific  power  which 
represents  the  energy  which  the  system  can  obtain  from 
the  food  is  also  very  constant. 

A  balanced  diet.  If  the  amount  and  kind  of  food  is  not 
well  selected,  an  excess  of  one  or  more  of  the  essential 
constituents  of  food  will  be  present  and  must  be  elimi- 
nated to  the  detriment  of  the  system.  For  instance,  a 
diet  composed  largely  of  meat  will  contain  more  protein 
matter  than  is  required  to  keep  the  tissues  in  good  con- 
dition. It  is  necessary  with  such  a  diet  to  consume  this 
excess  of  protein  matter  in  order  to  obtain  the  proper 
amount  of  fats  and  carbohydrates.  Such  a  diet  is  not 
well  balanced. 

The  standard  ration  gives  the  quantities  of  fats^  carbohy- 
drates^ and  protein  found  to  he  just  sufficient  to  sustain  a 
human  being  under  given  conditions  in  normal  health  and 
activity, 

23 


24  PURE  FOODS 

The  standard  ration.  The  daily  ration  found  by  most 
investigators  contains  100  gm.  of  protein,  100  gm.  of  fat, 
and  420  gm.  of  carbohydrates,  or  a  total  of  620  gm.  These 
weights  refer  to  the  solid  matter  only  of  the  food.  In  its 
ordinary  condition  about  three  times  this  amount  would  be 
required  because  ordinary  food  contains  a  large  amount  of 
water.  Expressed  in  ordinary  or  avoirdupois  weights,  this 
standard  ration  would  require  31^  oz.  of  protein,  3|^  oz.  of 
fat,  and  15  oz.  of  carbohydrates,  or  a  total  of  22  oz.  of 
solid  food,  which  is  equivalent  to  about  4  pounds  of  ordi- 
nary food.  The  3000  calories  of  energy  given  by  this 
amount  of  food,  if  liberated  as  heat,  are  capable  of  raising  10 
gallons  of  water  from  the  ordinary  temperature  to  the  boil- 
ing point ;  if  used  as  mechanical  energy,  2000  pounds,  or 
one  ton,  could  be  raised  4500  feet,  or  very  nearly  a  mile. 
It  seems  well-nigh  incredible  that  the  food  consumed  by 
the  average  human  being  during  twenty-four  hours  should 
liberate  so  much  energy. 

Interchangeable  foods.  While  a  great  many  of  the  tissues 
of  the  body  can  be  built  up  and  repaired  only  by  protein, 
which  for  this  reason  is  of  the  greatest  importance  in  the 
diet,  this  food  material  can  also  furnish  energy  and  there- 
fore serves  a  double  function  in  the  economy  of  nature. 
It  can  therefore  replace  to  a  certam  extent  fats  and  carbo- 
hydrates in  the  diet.  To  a  still  greater  extent,  fats  and 
carbohydrates  are  mutually  interchangeable.  It  is  there- 
fore possible  to  live  on  a  diet  in  which  the  proportion  of 
the  food  constituents  is  very  different  from  that  in  the  stand- 
ard or  normal  ration.  There  seems  also  to  be  a  very  great 
difference  in  individuals,  so  that  considerable  variation  is 
often  necessary  in  order  to  suit  idiosyncrasies  of  appetite, 
digestion,  and  assimilation.  The  consumption  of  excessive 
quantities  of  protein  seems  to  be  undesirable. 


STANDAED  RATIONS  AND  COST  OF  FOOD      25 

Rations  for  children.  During  periods  of  unusual  activity 
a  much  larger  amount  of  food  is  consumed,  while  the  aged 
and  children  consume  less.  The  ration  for  children  is  given 
in  Table  II.  It  will  be  observed  that  the  amount  of  pro- 
tein in  the  diet  of  the  child  is  relatively  larger  than  in  that 
for  the  adult.  The  child  one  year  and  a  half  old  requires 
24  per  cent  of  its  food  to  be  protein,  while  the  adult  re- 
quires only  16  per  cent.  The  child  is  building  up  a  new 
body  structure,  while  the  adult  is  simply  making  repairs. 

TABLE  II 
Rations  for  Children 


Age 

Protein 

Fat 

Carbo- 
hydrates 

Calories 

Grams 

Grams 

Grams 

1|  years   .... 

42.5 

35 

100 

910 

2  years     .    . 

45.5 

36 

110 

972 

3  years     .    . 

50 

38 

120 

1050 

4  years     .    . 

53 

41.5 

135 

1157 

5  years     .    . 

56 

43 

145 

1224 

8-9  years      . 

60 

44 

150 

1270 

12-13  years    . 

72 

47 

245 

1737 

14-15  years    . 

79 

48 

170 

1877 

Special  rations.  Table  III  gives  a  number  of  special 
rations  which  show  how  trained  athletes  are  capable  of 
utilizing  an  abnormally  large  amount  of  energy  derived 
from  food,  while  the  aged  cannot  utilize  as  much.  As  fats 
and  oils  produce  the  largest  amount  of  heat,  these  foods 
are  consumed  in  large  quantity  by  the  inhabitants  of  the 
coldest  climates  of  the  earth,  while  they  are  avoided  by  those 
living  in  the  torrid  zone.  Men  doing  a  large  amount  of  mus- 
cular work  also  consume  fats  for  the  production  of  energy. 


26 


PURE  FOODS 


TABLE  III 
Special  Rations 


Age  or  Employment 

Protein 

Fat 

Carbo- 
hydrates 

Calories 

Average  adult 

Average  of  seven  boat  crews  . 

Football  team 

United  States  Army  .... 

Old  man     ........ 

Old  woman 

Grams 
100 
155 

181 
85 
92 
80 

Grams 
100 
177 
292 
280 
45 
49 

Grams 
420 
440 
577 
500 
332 
266 

3030 
4085 
5740 
4944 
2149 
1875 

Excessive  consumption  of  protein.  A  considerable  amount 
of  evidence  has  been  brought  forth  to  show  that  the  amount 
of  protein  in  the  ordinary  diet  is  too  large.  Men  in  active 
life  and  also  trained  athletes  have  been  fed  for  long  periods 
on  diets  containing  half  the  usual  amount  of  protein,  re- 
maining vigorous  and  in  good  health  continually,  and  in 
some  cases  even  showing  a  very  marked  increase  in  strength 
and  endurance.^  While  the  number  of  experiments  con- 
ducted has  not  been  sufficient  to  prove  conclusively  that 
the  amount  of  protein  consumed  is  unnecessarily  large,  the 
evidence  at  hand  renders  it  very  probable  that  we  are 
consuming  about  twice  as  much  meat  and  other  highly 
nitrogenous  food  as  is  necessary.  The  stimulating  effect 
of  such  a  diet  undoubtedly  accounts  for  the  tendency  of 
mankind  for  centuries  to  consume  large  quantities  of  meat, 
while  only  recently  has  scientific  investigation  begun  to 
show  that  the  carbohydrates  and  fats  of  our  diet  give  the 
greater  endurance  and  strength. 

Coefficient  of  digestibility.  It  must  be  borne  in  mind  when 
considering  dietaries  that  the  food  consumed  is  seldom  or 

1  See  Chittenden,  The  Nutrition  of  Man. 


STAND AED  KATIONS  AND  COST  OF  FOOD      27 

never  completely  digested,  although  the  percentage  so 
utilized  by  the  system  is  in  many  cases  surprisingly  large, 
as  may  be  observed  from  an  inspection  of  Table  IV. 


TABLE  IV 

COEPFICIENT    OF    DIGESTIBILITY   OF    NuTRIENTS    IN   FoODS 


Food 

Protein 

Fats 

Carbo- 
hydrates 

Bananas  

Beans 

Beef 

Per  cent 
85 
80 
98 
88 
83 
97 
83 
98 
75 

91 

Per  cent 
90 
98 
98 
90 

95 

98 

95 

Per  cent 
90 
97 

Bread,  white 

whole  wheat    .... 

Milk  and  butter 

Peas 

98 
95 
98 
95 

Pork 

Potatoes,  Irish 

Sugar   

Average  common  foods  .    .    . 

99 
98 
98 

The  percentages  given  in  this  table  do  not  show  the  ease 
with  which  these  foods  are  digested.  They  simply  give  the 
proportion  of  the  food  which  is  finally  digested,  whether 
the  effort  on  the  part  of  the  digestive  system  is  great  or 
small.  It  is  also  assumed  that  the  food  is  properly  masti- 
cated and  that  excessive  amounts  are  not  consumed.  It  may 
be  stated,  in  general,  that  the  protein  matter  of  vegetables 
is  not  as  digestible  as  that  of  meats. 

The  method  of  calculating  the  daily  ration  from  a  mixed 
diet  is  shown  in  Table  Y. 

A  record  of  the  amount  of  each  article  of  food  consumed 
during  a.  week  was  kept  and  the  weight  of  each  of  the 
constituents  calculated  from  the  percentage  composition 
of  the  food,  and  also  the  total  calorific  value.    Allowance 


28 


PURE  FOODS 


TABLE  V 
Week's  Food  for  Four  Adults 


Food 

Pounds 

Protein 

Fats 

Carbohy- 
drates 

Calories 

Cost 

Sugar    .    .    . 
Prunes . 

101 

2 
1 

3 
1 

1 
I 
f 

H 

3 

2 

f 
14 

2 

f 
6 
3 

1 
4 

2 
1 
9 

10t\ 

Grams 

17.2 

40 
231 

13.5 

33.3 

50 

22 

7 

100 

21 
172 

22 

460 

3 

14 
3 

48 
129.3 

44 
270 
140 
115 
460 

Grams 

10 

77 

1,155 

2.7 

5 

12 

1.2 
80 
15 
64.4 
28 
560 
.8 
10 

.8 

24 

132 

24 

270 

m 

38 
45 

Grams 

4,756 

564 

340 

131.2 
338 
150 
17 

132 

70 
696 

20 

88 

20 
414 
718.5 
300 

616 

3,042 

19,500 

2,378 

1,655 

1,650 

10,512 

467 

1,645 

800 

110 

1,190 

780 

1,300 

600 

10,000 

210 

520 

210 

1,950 

3,615 

1,600 

3,620 

3,720 

825 

14,805 

Cents 
54 

22 

Corn  flakes  . 
Fish.    .    .    . 
Butter  .    .    . 

20 
54 

87 

Lima  beans  . 
Malt.    .    .    . 

7 
13 

Uneedas  .    . 
Lettuce     .    . 

Effffs.    .    .    . 

5 
16 
25 

Blackberries 
Beef 

54 
32 

Condensed  mill 
Milk     .    .    . 

^ 

10 
113 

Onions .    .    . 

7 

Strawberries 
Cauliflower  . 
Potatoes  .    . 
Bread   .    .    . 

36 
15 
24 
15 

Pretzels    .    . 
Leg  of  lamb 
Oatmeal    .    . 
Herring    .    . 
Flour    .    .    . 

5 
64 
10 
17 
27 

Total  per  week 
Total  per  day    . 

2,418 
345 

2,599 
371 

12,412 
1,773 

84,662 
12,095 

731 
104 

For  one  adult    . 

2| 

86 

93 

443 

3,024 

26 

Standard  ration 

100 

100 

420 

3,030 

must  be  made  in  preparing  such  a  table  for  unconsumed 
portions  and  the  necessary  waste  in  preparing  food  for  the 
table.    From  the  total  of  each  column  the  amount  per  day 


STANDAED  RATIONS  AND  COST  OF  FOOD      29 

for  each  individual  can  be  calculated.  The  daily  ration  in 
this  case  was  86  gm.  of  protein,  93  gm.  of  fats,  443  gm.  of 
carbohydrates,  and  3024  calories,  which  is  very  nearly  identi- 
cal with  the  standard  ration,  although  a  little  low  in  protein. 
Comparative  cost  of  foods.  It  is  evident  that  a  given  food 
constituent,  such  as  protein,  can  be  obtained  from  a  large 
variety  of  foods.  On  account  of  the  difficulty  of  producing 
a  given  food,  its  scarcity,  or  a  very  desirable  flavor,  the 
cost  of  the  same  amount  of  protein  may  vary  within  very 
wide  limits.  In  order  to  show  the  great  difference  in  the 
cost  of  foods.  Table  VI  has  been  prepared.  The  cost  of  a 
sufficient  amount  of  each  food  to  give  3000  calories  has  been 

TABLE  VI 
Cost  of  a  Daily  Ration  of  a  Single  Food 


Food 

•     Price 

Cost  of  3000 
calories 

Flour  

Oatmeal 

Cents 
3^  per  pound 
5    per  pound 

8  per  pound 
5    per  pound 

20    per  pound 

9  per  quart 
40    per  dozen 
18    per  pound 

14  per  pound 
80    per  bushel 

15  per  pound 

14  per  pound 
13    per  pound 
35    per  pound 

250    per  gallon 

15  per  dozen 
12    per  dozen 

Cents 

6.3 
8 
15 

Sugar  

Beef 

Milk 

Eggs 

Cheese 

Eish 

8 
58 
38 

184 
26 

101 

Potatoes 

Cauliflower 

Onions 

12 
215 
215 

Strawberries 

Butter 

250 

29 

Olive  oil 

Bananas 

Oysters 

23 

40 

553 

30 


PUEE  FOODS 


calculated.  As  this  is  the  amount  needed  during  twenty- 
four  hours  by  the  average  adult,  the  figures  given  show  the 
cost  of  a  day's  ration  of  each  article  of  food. 

While  living  on  a  single  article  of  food  for  even  one  day 
would  not  be  very  desirable,  and  would  be  actually  done 
only  under  very  unusual  conditions,  the  calculation  of  the 
cost  of  such  a  day's  ration  shows  very  clearly  the  compara- 
tive cost  of  the  various  articles  of  food.  A  study  of  this 
list  shows  that  the  price  per  pound  gives  very  little  idea 
of  the  comparative  economy  of  buying  a  given  food.  Beef, 
for  instance,  at  20  cents  a  pound  is  a  very  much  cheaper 
food  than  fish  at  14  cents  per  pound,  since,  when  buying 
beef,  58  cents  will  buy  as  much  nutritive  value  as  fl.Ol 
will  purchase  when  buying  fish.  The  cheapest  articles 
of  food  cannot  always  be  purchased,  however,  because 
the  proper  balance  between  the  fats,  carbohydrates,  and 
protein  must  be  maintained,  and  some  foods  must  be 
used  on  account  of  their  beneficial  effect  on  the  digestive 
system. 

The  following  table  shows  how  the  same  nutritive  value 
as  well  as  the  correct  proportion  of  the  various  food  constit- 
uents can  be  obtained  at  a  very  great  difference  in  cost. 


TABLE  VII 
Cost  of  a  Day's  Food  of  Beefsteak,  Potatoes,  and  Butter 


Food 

Cost 

Protein 

Fat 

Carbo- 
hydrates 

Mineral 
matter 

Calories 

Steak,  1^  lb.     .    . 
Potatoes,  5  lb.  .    . 
Butter,  2  oz.     .    . 

Cents 

30 

8 

5 

Grams 

87 
40 

Grams 
52 

48 

Grams 
339 

Grams 

4 

20 

937 

1630 

450 

Total  .... 

43 

127 

100 

339 

24 

3017 

STANDARD  RATIONS  AND  COST  OF  FOOD      31 


TABLE  YII  (Continued) 
Cost  of  a  Day's  Food  of  Eggs,  Bread,  and  Butter 


Food 

Cost 

Protein 

Fat 

Carbo- 
hydrates 

Mineral 
matter 

Calories 

Eggs,  1  doz.      .    . 
Bread,  If  loaves  . 
Butter,  2  oz.     .    . 

Cents 

38 

6 

5 

Grams 
66 

48 

Grams 
52 
4.5 

48 

Grams 
325 

Grams 
5 
9 

838 

1650 

450 

TOTAI 

49 

114 

104.5 

325 

14 

2938 

Cost  of  a  Day's  Food  of  Fish;  Potatoes,  Butter,  and 
Olive  Oil 


Food 

Cost 

Protein 

Fat 

Carbo- 
hydrates 

Mineral 
matter 

Calories 

Bluefish,  2  lb.  .    . 
Potatoes,  4f  lb.     . 
Butter,  2  oz.     .    . 
Olive  oil,  2  oz.      . 

Cents 

40 

8 

5 

5 

Grams 
86 
39 

Grams 
5 

48 
54 

Grams 
328 

Grams 

4.7 

17.8 

410 

1575 

450 

528 

Total  .... 

58 

125 

107 

328 

22.5 

2963 

Cost  of  a  Day's  Food  of  Oysters,  Bread,  Butter,  and 
Olive  Oil 


Food 

Cost 

Protein 

Fat 

Carbo- 
hydrates 

Mineral 
matter 

Calories 

Oysters,  2|  lb. .    . 
Bread,  1^  loaves  . 
Butter,  2  oz.     .    . 
Olive  oil,  2  oz. 

Cents 

107 

6 

5 

5 

Grams 
65 
42 

Grams 
9.1 
3.9 

48 

54 

Grams 

35.8 

284.5 

Grams 
6.5 

7.8 

575 

1440 

450 

528 

Total  .... 

123 

107 

115 

320.3 

14.3 

2993 

32 


PUEE  FOODS 


TABLE  VII  (Concluded) 
Cost  of  a  Day's  Food  of  Milk,  Bread,  and  Butter 


Food 

Cost 

Protein 

Fat 

Carbo- 
hydrates 

Mineral 
matter 

Calories 

Milk,  2\  qt.  .    .    . 
Bread,  1|  loaves  . 
Butter,  1  oz.     .    . 

Cents 

18 

6 

2 

Grams 
73 
40 

Grams 
69 
3.7 
30 

Grams 

88 
267 

Grams 
13.4 

7 

1430 

1350 

225 

Total  .... 

26 

113 

102.7 

355 

20.4 

3005 

CHAPTER  IV 

MILK 

Importance  of  milk  as  a  food.  Milk  is  one  of  the  most 
largely  used  of  human  foods.  The  city  of  New  York  uses 
2,000,000  quarts  of  milk  per  day;  500,000  gallons  come 
pouring  into  the  city  every  twenty-four  hours,  and  are 
consumed  by  the  population.  If  this  amount  of  milk  were 
divided  equally,  every  person  would  have  one-half  quart 
of  milk  per  day.  This  amount  is  sufficient  to  constitute 
10  per  cent  of  the  standard  daily  ration,  and  when  we  con- 
sider that  not  over  half  of  the  population  of  the  city  is 
consuming  the  standard  daily  ration,  because  that  is  the 
ration  for  an  adult  in  vigorous,  active  life,  it  is  evident 
that  milk  constitutes  a  much  larger  percentage  of  the  food 
consumed  by  the  people  of  New  York.  It  is  of  still  more 
importance  because  it  is  almost  the  entire  food  of  young 
children,  and  is  a  large  part  of  the  diet  of  the  child  up  to 
ten  years  of  age,  and  frequently  beyond.  In  addition,  it  is 
the  chief  source  of  nourishment  of  invalids  and  the  aged,  — 
in  fact,  of  any  person  whose  state  of  health  is  such  that  he 
needs  an  easily  digested,  highly  nutritious  food.  Without  it 
a  large  number  of  the  sick  and  invalid  would  undoubtedly 
perish.  It  is  probably  true  that  an  adulterated  and  im- 
properly handled  milk  supply  will  produce  more  suffering, 
sickness,  and  death  than  has  resulted  from  the  adulteration 
of  all  other  foods  combined.  There  is  no  other  food  product 
the  condition  of  which  produces  such  a  marked  effect  on 
the  death  rate  of  a  community.   The  great  reduction  in  the 

33 


34  PUEE  FOODS 

death  rate  of  young  children  in  American  cities  during 
recent  years  is  well  known  to  be  due  to  the  great  advance 
made  in  our  knowledge  of  the  composition  and  methods  of 
transportation  and  preservation  of  milk. 

Constituents  of  milk.  Among  common  foods  milk  prob- 
ably approaches  nearest  the  ideal  food.  It  contains  all  the 
important  constituents  of  a  complete  food,  —  protein,  fats, 
carbohydrates,  and  mineral  matter.  When  milk  is  allowed 
to  stand  quietly  for  some  time,  the  fat  rises  to  the  top  and 
is  removed  in  the  form  of  cream,  from  which  the  fat  is  sep- 
arated in  a  still  purer  form  as  butter.  When  the  skim  milk 
sours,  the  protein,  known  as  casein,  separates  as  curd.  The 
various  kinds  of  cheese  contain  nearly  all  of  the  protein  of 
the  milk  as  well  as  more  or  less  of  the  fat.  When  the  curd 
has  been  removed,  there  remains  a  somewhat  sweetish  liquid 
known  as  whey.  This  contains  the  sugar  anfl.  mineral  mat- 
ter of  the  milk.  By  boiling  the  whey  until  a  great  deal  of 
the  water  has  been  expelled,  and  inserting  strings  or  sticks 
of  wood,  the  sugar  crystallizes  out  and  is  broken  up  or 
powdered,  to  be  sold  as  milk  sugar.  The  remaining  liquid 
contains  most  of  the  mineral  matter.  By  boiling  until  the 
water  is  entirely  volatilized  a  solid  remains,  which  can  be 
heated  to  redness  without  being  entirely  burned  up.  This 
residue,  which  is  incombustible,  is  the  mineral  matter  or  ash 
of  the  milk.  Cow's  milk,  which  is  the  milk  most  largely  used, 
varies  considerably  in  composition,  depending  on  the  season, 
breed,  age,  method  of  feeding,  etc.,  of  the  animal.  The  com- 
position of  the  milk  of  a  mixed  herd  is  much  more  constant, 
the  figures  given  in  Table  VIII  referring  to  such  milk. 

The  largest  constituent  is  water.  The  solid  constituents 
are  not  present  in  the  proportion  given  for  the  standard 
adult  ration,  the  protein  being  present  in  much  larger  pro- 
portion, so  that  it  approaches  more  nearly  the  ration  given 


MILK 


35 


for  children,  who  need  more  protein  for  the  growing  tissues. 
When  milk  is  used  as  a  food  for  the  adult,  sugar  or  some 
starchy  food  such  as  bread  should  be  eaten  with  it.  In  pro- 
tein cow's  milk  is  much  richer  than  human  milk,  while 
human  milk  is  much  richer  in  sugar. 

TABLE  VIII 
Composition  of  Milk 


Constituents 

Cow's  milk 

Human  milk 

Calories 

325 

Water      

Per  cent 

87.3 

12.7 

3.6 

3.8 

4.5 

.1 

.7 

Per  cent 
87.4 

Total  solids 

12.6 

Fat . 

Protein 

3.78 
2.29 

Milk  sugar 

6.21 

Lactic  acid 

Ash 

.31 

Batio  of  Constituents  of  Cow's  Milk 
Protein  100  :  Fat  100  :  Carbohydrates  125 


Modified  milk.  It  is  evident  that  if  cow's  milk  is  to  be 
modified,  so  as  to  be  used  for  -infants,  the  amount  of 
protein  must  be  reduced.  This  is  done  by  diluting  the 
milk  to  a  considerable  extent.  This  reduces  the  fat  and 
the  sugar.  These  two  constituents  must  then  be  increased 
by  adding  cream  and  milk  sugar ;  so  that  in  adapting  cow's 
milk  to  the  feeding  of  infants  it  is  diluted  and  then  en- 
riched with  cream  and  milk  sugar,  and  made  to  correspond 
very  closely  to  human  milk,  the  natural  food  for  the  child. 

High  protein  content.  Milk  must  be  classed  as  a  high 
protein  food.  The  amount  of  protein  given  in  Table  VIII, 
3.8  per  cent,  seems  very  small,  but  account  must  be  taken 


36 


PUEE  FOODS 


of  the  fact  that  there  is  present  in  the  milk  but  12.7  per 
cent  of  solids,  so  that  nearly  one  third  of  this  solid  matter 
is  protein.  Meats  and  fish  are  the  only  foods  which  exceed 
milk  in  the  amount  of  protein  present.  Two  and  a  half 
quarts  of  milk  contain  as  much  protein  matter  as  a  pound 
of  meat,  and  in  addition  the  milk  contains  sugar  and  fat. 
As  a  food  two  and  a  half  quarts  of  milk  are  worth  a  great 
deal  more  than  a  pound  of  meat.  If  one  could  live  on  milk 
alone,  less  than  four  quarts  a  day  would  suffice,  and  at 
8  cents  per  quart,  it  would  cost  32  cents  per  day.  Com- 
pared with  other  high  protein  foods,  this  is  a  very  low  cost, 
as  may  be  seen  from  an  inspection  of  Table  VI.  From  the 
following  table  it  may  be  seen  that  milk  alone  is  a  poorly 
balanced  food,  with  an  excess  of  protein,  but  that  the  addi- 
tion of  bread  and  butter  improves  the  ration  and  also  reduces 
Lthe  cost. 
TABLE  IX 

Daily  Ration  of  Milk 


Cost 


Protein 


Fats 


Carbo- 
hydrates 


Ash 


Calories 


4  quarts 


Cents 


Grams 
133 


Grams 
126 


Grams 
157 


Grams 
24 


2920 


Daily  Ration 

OF  Bread,  Butter,  ane 

>  Milk 

Milk,  2qt.    .    .    . 
Bread,  1\  loaves  . 
Butter,  1  oz .    .    . 

16 

6 

2 

m 

50 

63 

5 

30 

78 
257 

12 
5 

1460 

1355 

225 

Total  .... 

24 

116 

98 

335 

17 

3040 

A  staple  food.  Milk  is  classed  as  a  "  staple  food,"  because 
it  is  one  which  can  be  consumed  continually  by  a  very 
large  number  of  human  beings  without  detriment  or  par- 
ticular dislike.    Only  when  the  adult  has  been  compelled 


MILK 


37 


to  live  on  milk  exclusively  for  a  considerable  period  does 
he  absolutely  lose  his  desire  for  and  enjoyment  of  milk. 

Variations  in  composition  of  milk.  The  figures  given  rep- 
resent the  average  composition  of  milk.  The  natural  varia- 
tions are  quite  large.  The  total  solids  may  vary  from  9 
to  17  per  cent;  that  is,  one  milk  may  be  nearly  twice  as 
rich  as  another,  the  corresponding  amounts  of  water  being 
91  and  83  per  cent.  The  fat  may  vary  from  1.67  to  6.4 
per  cent,  the  milk  sugar  from  2  to  6  per  cent,  the  protein 
from  2  to  over  6  per  cent,  and  the  ash  from  .35  to  1.2  per 
cent.  On  account  of  these  large  variations  in  the  composi- 
tion of  milk,  consumers  would  be  defrauded  unless  its  sale 
were  regulated  by  law.  A  minimum  of  12  to  13  per  cent 
of  total  solids  and  3  to  3^  per  cent  of  fat  is  usually  required. 
If  the  milk  contains  less  than  these  amounts,  for  whatever 
cause,  it  is  considered  adulterated,  so  that  its  sale  is  illegal. 

Variations  in  New  York  City  milk.  The  following  table 
shows  the  variation  in  percentage  of  fat  in  milk  sold  in 
New  York  City : 

TABLE  X 
Percentage  of  Fat  in  Milk  sold  in  New  York  City 


Per  cent 

Per  cent 

Per  cent 

Milk  Co.  No.  1    . 

8^,  bottled     .... 

3.8 

Milk  Co.  No.  2-  . 

8)^,  bottled     .... 

3.8 

3.8 

3.6 

Milk  Co.  No.  3    . 

8^,  bottled     .... 

3.4 

3.6 

3.5 

Milk  Co.  No.  3    . 

15^,  bottled  (certified) 

4.8 

Milk  Co.  No.  4    . 

8j^,  bottled     .... 

3.3 

Milk  Co.  No.  5    . 

8^,  bottled     .... 

3 

2.5 

6^,  in  cans     .... 

3.2 

3.2 

3.1 

The  fat  varies  much  more  than  the  other  constituents  of 
milk,  the  protein,  milk  sugar,  and  ash  remaining  quite 
constant.    The  variation  in  the  milk  of  Dairy  Company 


38 


PURE  FOODS 


No.  2  occurred  within  a  few  days.  The  milk  of  Dairy 
Company  No.  5,  containing  only  2.5  per  cent  fat,  was 
below  the  legal  standard,  and  whether  it  was  watered  or 
whether  the  cows  produced  such  very  thin  milk,  still  its 
sale  was  illegal,  and  the  company  selling  it  was  subject  to 
a  fine.  The  6-cent  milk  is  low  in  fat  also,  but  just  above 
the  legal  standard. 

Cream.  The  fat  of  milk  is  removed  and  sold  separately 
as  cream.  It  may  be  separated  from  the  milk  in  two  ways,  — 
either  by  allowing  it  to  rise  and  skimming  it  from  the  top 
of  the  milk,  or  by  means  of  mechanical  separators,  which 
separate  the  fat  very  completely  from  the  fresh  whole  milk. 
We  have,  then,  two  kinds  of  cream,  the  "  separator  "  cream 
and  the  "  light "  cream.  The  foUowiag  table  shows  their 
composition : 

TABLE  XI 


Separator  cream 
Light  cream 


Fat 


Per  cent 
38-46  (av.  42) 
8.6-21.6  (av.  13. 


other  solids 


Per  cent 
6.3 
8.25 


Water 


Per  cent 
51.7 
77.85 


Comparative  cost.  The  comparative  cost  of  milk,  cream, 
and  butter,  based  on  the  calorific  values,  is  given  in  the 
following  table : 

TABLE  XII 

COMPARATIVK    CoST   OF   MiLK,  CuEAM,  AND   BuTTKll 


Cost 

Calories 

Cost  of 
1(X)0  calories 

Cream,  ^  pt 

Milk,  1  qt 

Butter,  lib 

Cents 

12 

8 

35 

1044 

730 

3605 

Cents 

11.49 

10.96 

9.71 

MILK  39 

Thus  we  find  that  cream  is  the  most  expensive  food  of 
this  kind  that  we  can  buy,  milk  is  the  next,  and  butter  is 
the  cheapest. 

^  Skim  milk.  After  the  cream  has  been  separated,  there 
remains  skim  milk,  which  contains  nearly  the  same  amount 
of  protein,  milk  sugar,  and  ash  as  the  sweet  milk,  while 
only  a  trace  of  fat  remains.  In  New  York  and  other  cities 
it  is  illegal  to  sell  skim  milk.  This  is  unfortunate,  because 
skim  milk  is  an  excellent  food.  It  lacks,  of  course,  the 
fat,  but  contains  protein,  carbohydrates,  and  ash,  which 
make  it  a  valuable  food  which  could  be  sold  at  a  fairly 
low  price.  The  danger  is  that  it  would  be  sold  as  whole 
milk,  so  that  the  public  would  be  deceived.  If  the  golden 
rule  were  observed  and  every  one  were  honest,  unques- 
tionably we  should  get  along  better.  If  every  one  would 
sell  skim  milk  as  skim  milk,  its  sale  would  undoubtedly  be 
allowed,  and  this  cheap  food  product  would  be  available. 
It  is  sold,  however,  but  not  as  skim  milk.  Most  of  it  is  sold 
as  buttermilk.  The  buttermilk  is  prepared  by  adding  to 
the  sweet  skim  milk  a  pure  culture  of  the  bacteria  which 
produce  lactic  acid,  and  as  these  bacteria  grow  the  milk 
curdles.  Some  sweet  whole  milk  is  usually  added  and  the 
mixture  churned  in  order  to  obtain  a  product  resembling 
the  buttermilk  obtained  in  the  creameries. 

^  Evaporated  milk.  The  skim  milk  is  also  evaporated 
and  reduced  to  a  powder,  which  is  known  as  evaporated 
milk.  It  contains  all  the  solids  of  the  skim  milk,  the  water 
only  having  evaporated.  It  is  being  used  more  and  more 
by  the  wholesale  food  houses,  who  mix  it  with  flour  in 
preparing  the  special  self-raising  flours  which  are  used  for 
making  pancakes  and  similar  foods.  It  is  more  convenient 
to  have  the  milk  in  this  form  mixed  with  the  flour,  and 
is  probably  somewhat  cheaper  than  using  fresh  milk. 


40  PURE  FOODS 

Casein.  The  casein  is  also  separated  from  the  milk  and 
powdered,  so  that  it  may  be  added  to  other  foods,  in  order 
to  increase  the  proportion  of  protein.  A  less  pure  casein  is 
used  for  other  purposes.  A  cold-water  paint  is  made  from 
such  casein.  Casein  will  dissolve  in  water,  and,  if  spread 
out  like  paint,  the  solution  will  dry  and  form  a  hard  film. 
By  mixing  pigments  with  it,  paints  of  various  colors  are 
obtained  that  will  dissolve  in  water.  Where  a  surface  is  not 
exposed  to  dampness,  this  water  paint  is  quickly  applied 
and  is  convenient. 

i 

EXPERIMENTS 

8.  Constituents  of  milk.  Place  about  25  ccm.  of  milk  in  a  porcelain 
evaporating  dish  and  heat  on  the  water  bath  until  dry.  The  residue 
consists  of  the  fat,  casein,  sugar,  and  mineral  matter  of  the  milk. 
Add  a  few  cubic  centimeters  of  ether  and  stir  the  solid  residue  with 
a  glass  rod  so  as  to  dissolve  the  fat.  Pour  the  clear  ether  solution 
on  a  watch  crystal  and  allow  the  ether  to  evaporate.  The  residue  is 
the  butter  fat  of  the  milk.  By  repeating  the  extraction  with  ether 
all  of  the  fat  may  be  removed  from  the  milk  residue. 

9.  Casein  and  milk  sugar.  Heat  about  200  ccm.  of  skim  milk  to 
90°  F.  and  add  a  few  drops  of  rennet  or  a  few  cubic  centimeters  of 
acetic  acid,  and  allow  to  stand  in  a  warm  place  until  the  milk  is 
curdled.  The  curd  is  the  casein  or  protein  of  the  milk,  and  may  be 
separated  from  the  whey  by  filtering  through  cheesecloth.  Make 
the  whey  slightly  alkaline  by  adding  limewater  and  testing  with 
red  litmus  paper  until  the  paper  has  turned  blue.  Evaporate  to 
about  half  the  bulk,  or  until  the  albumen  has  been  precipitated. 

Filter  and  again  evaporate  to  about  one  sixth  the  bulk.  Cool,  add 
an  equal  volume  of  methyl  or  wood  alcohol,  and  allow  to  stand  for 
several  hours  or  until  a  crystalline  precipitate  is  formed.  This  is 
milk  sugar.    Filter  it  off  and  dry. 

10.  Test  for  borax.  Test  the  milk  for  borax  or  boric  acid  in  the 
following  manner:  25  ccm.  of  milk  is  placed  in  a  porcelain  dish, 
a  little  limewater  added,  and  the  whole  evaporated  to  dryness.  Heat 
the  dish  to  redness  with  the  Bunsen  burner.    The  milk  residue 


MILK  41 

decomposes  and  burns.  On  continued  heating,  the  charcoal  burns  and 
leaves  a  white  residue.  This  is  the  ash  or  mineral  matter  in  the  milk, 
plus  the  lime  which  was  added.  If  borax  or  boric  acid  had  been  added 
to  the  milk  as  a  preservative,  it  would  be  present  in  this  residue. 

The  preservative  may  be  tested  for  as  follows :  Dissolve  the  resi- 
due in  a  few  drops  of  hydrochloric  acid  and  moisten  a  strip  of  tur- 
meric paper  in  the  solution.  Dry  the  paper,  being  careful  not  to  heat 
it  above  100°  C.  The  development  of  a  bright  red  color  indicates  the 
presence  of  borax  or  boric  acid.  The  red  color  is  changed  to  a  dark 
green  by  a  drop  of  ammonia.  If  a  large  amount  of  preservative  is 
present,  the  milk  may  be  tested  directly  after  adding  a  few  drops  of 
hydrochloric  acid. 

The  test  may  also  be  carried  out  in  the  following  simple  manner : 
Acidify  the  milk  with  a  few  drops  of  hydrochloric  acid  and  hang  a 
strip  of  turmeric  paper  so  that  the  lower  edge  is  moistened  with  the 
milk.  After  six  or  eight  hours  a  cherry-red  color  will  appear  at  the 
border  of  the  moist  portion  if  boric  acid  is  present. 

In  order  to  become  familiar  with  the  delicacy  of  the  test,  dissolve 
1  gm.  of  borax  in  100  ccm.  of  pure  milk.  Dilute  this  solution  by 
adding  10  ccm.  to  90  ccm.  of  pure  milk.  Repeat  the  dilution,  using 
10  ccm.  of  the  last  solution  and  90  ccm.  of  pure  milk.  In  this 
manner  samples  of  milk  will  be  obtained  having  1  part  of  borax 
in  100,  1000,  and  10,000  parts  of  milk.  Test  these  samples  of  milk 
in  the  manner  indicated  and  observe  the  delicacy  of  the  test. 
Also  allow  the  milk  to  stand  several  days  in  order  to  observe  the 
preservative  action. 

11.  Test  for  formaldehyde.  Test  milk  for  formaldehyde  in  the  fol- 
lowing manner :  Place  10  ccm.  of  the  milk  in  a  test  tube  and  pour 
carefully  down  the  side  of  the  inclined  tube  5  ccm.  of  concentrated 
commercial  sulphuric  or  pure  sulphuric  acid  to  which  a  little  ferric 
chloride  has  been  added.  A  violet  coloration  is  produced  at  the 
junction  of  the  two  liquids  if  formaldehyde  is  present. 

Also  make  the  test  in  the  following  manner :  15  ccm.  of  the  milk 
is  placed  in  a  small  casserole  or  other  suitable  dish.  Add  an  equal 
volume  of  commercial  hydrochloric  acid  or  pure  acid  to  which  a  little 
ferric  chloride  has  been  added.  The  mixture  is  slowly  heated  to  the 
boiling  point.  It  is  continually  stirred  or  agitated  to  avoid  charring, 
as  well  as  the  formation  of  curd.  A  violet  coloration  is  produced 
if  formaldehyde  is  present.   In  this  experiment  as  well  as  in  the  test 


42  PURE  FOODS 

for  borax  it  is  very  important  that  the  test  be  carried  out  by  the 
beginner  on  samples  of  milk  containing  known  quantities  of  the 
preservative.  Samples  of  milk  containing  1  part  of  formaldehyde 
in  1000, 10,000,  and  50,000  should  be  prepared.  For  this  purpose  the 
commercial  40  per  cent  formaldehyde  solution  may  be  used.  5  ccm. 
is  diluted  with  water  to  20  ccm.,  and  1  ccm.  of  this  solution  is  added 
to  99  ccm.  of  pure  milk.  On  diluting  10  ccm.  of  this  milk  with  90 
ccm.  of  pure  milk,  and  again  diluting  20  ccm.  with  80  ccm.  of  pure 
milk,  samples  are  obtained  containing  1  part  of  formaldehyde  in 
1000,  10,000,  and  50,000  of  milk.  These  samples  should  be  tested 
and  then  set  aside  to  observe  the  keeping  qualities. 


CHAPTER  V 


BACTERIA  IN  MILK 


Bacteria.  Except  under  very  unusual  conditions,  milk 
invariably  contains  another  constituent,  namely  bacteria. 
These    are  minute,    microscopic,    single-celled    organisms. 


10 


11 


^0, 


C33     O 


12 


,^ 


%, 
'^^ 


0 


13 


-in 


-:: 
v.  n 

9 


l#r 


14 


Fig.  3.    A  Variety  of  Bacteria  likely  to  be  found  in  Milk^ 

1  and  2,  typhoid  bacillus  (P/eifer) ;  3,  pus  and  pus  cocci ;  4,  B.  Dysenterie 
{Shigar) ;  5,  Proteus  vulgaris;  6,  Clostridium  hutyricus;  7,  9,  10,  11,  types 
of  common  lactic  bacteria  {Conn);  8,  a  coccus  without  influence  on  milk 
(Conn) ;  12,  13,  14,  three  bacilli  producing  slimy  milk  (12,  Marshall ;  13 
and  14,  Conn) 

which  in  a  favorable  environment  flourish  and  multiply 
with  enormous  rapidity.  They  vary  in  shape  from  circular 
to  oval  or  elongated  rodlike  bodies.  They  are  capable  of 
more  or  less  motion  when  in  liquids,  sometimes  having  a 


1  Illustration  reproduced  from  Conn's  "  Bacteria  in  Milk  and  its  Products." 

43 


44      "'  PUEE  FOODS 

number  of  hairlike  flagella  which  vibrate  and  propel  the 
bacteria.  Although  so  small  that  they  are  visible  only 
through  the  microscope,  they  are  very  important  factors  in 
human  life.  Many  of  man's  most  violent  and  fatal  diseases 
are  produced  by  bacteria.  A  great  many  very  important 
chemical  transformations  are  also  brought  about  by  these 
organisms.  All  of  the  enormous  quantities  of  alcohol  man- 
ufactured every  year  are  produced  by  the  yeast  ferments. 
Most  of  our  soils  would  be  arid  and  unproductive  without 
the  activity  of  bacteria.  The  various  processes  of  decay 
are  all  brought  about  by  their  action. 

The  food  of  bacteria.  These  minute  organisms  are  nour- 
ished in  a  manner  very  similar  to  that  of  human  beings ;  that 
is,  the  food  which  they  consume  is  eliminated  only  after  it 
has  been  transformed  into  some  other  chemical  compound. 
During  this  transformation  the  energy  necessary  for  the 
life  of  the  bacteria  is  liberated.  A  given  bacterium  always 
transforms  its  food  into  a  definite  chemical  compound.  It 
is  therefore  possible,  by  selectmg  the  proper  bacterium,  to 
transform  the  starch  of  any  of  the  grains  into  alcohol,  and 
on  this  fact  is  founded  the  enormous  industries  manufac- 
turing fermented  alcoholic  beverages  and  pure  alcohol.  By 
using  another  organism  the  alcohol  may  be  transformed 
mto  acetic  acid,  so  that  vinegar  is  produced.  Generally  the 
food  required  by  bacteria  is  some  form  of  organic  matter, 
which  must  be  in  solution  or  at  least  quite  moist.  When 
bacteria  which  can  flourish  in  the  human  body  and  live  on 
such  organic  matter  as  is  present  in  the  tissues  of  the  body 
gain  entrance,  disease  usually  results  because  the  tissues 
are  being  destroyed.  Such  bacteria  are  called  disease  bac- 
teria, such  as  typhoid,  scarlet  fever,  etc.  Most  bacteria  can- 
not live  under  these  conditions,  but  flourish  on  dead  matter 
outside  of  living  bodies  and  are  therefore  quite  harmless. 


BACTERIA  IN  MILK 


45 


Bacteria  flourish  in  milk.  The  composition  of  milk  is 
such  that  many  bacteria  flourish  and  grow  very  rapidly 
after  gaining  entrance.  Indeed,  few  or  any  other  foods  offer 
such  favorable  conditions  for  their  growth.  This  is  largely 
because  milk  is  a  liquid  containing  a  variety  of  food  mate- 
rial in  solution.  Bacteria 
are  so  widely  distributed, 
being  always  present  in 
the  air,  water,  dust,  and 
on  the  surface  of  all 
ordinary  utensils,  that 
they  very  rapidly  gain 
entrance  to  milk,  even 
though  considerable  care 
is  exercised  to  exclude 
them.  By  exercising  the 
most  extraordinary  pre- 
cautions it  is  possible  to 
draw  from  healthy  cows 
milk  which  contains  no 
bacteria,  so  that  they 
cannot  be  said  to  be  a 
natural  constituent  of 
cow's  milk.  As  it  has 
not  yet  been  found  prac- 
ticable to  draw  milk  in 
this  manner  nor  to  eliminate  the  bacteria  after  milking,  it 
may  be  said  that  bacteria  are  a  normal  constituent  of  milk 
as  consumed  by  human  beings. 

Action  of  bacteria  on  milk.  It  is  very  important  to  learn 
the  character  of  the  bacteria  which  are  found  in  milk,  and 
their  effect  upon  its  properties.  If  they  are  absolutely  ex- 
cluded, it  is  found  that  milk  does  not  become  sour,  but 


Fig.  4.    Old-Style  Barn 

Dirty  and  unsanitary.    Particles  of  dust 
contain  thousands  of  bacteria 


46  PUEE  FOODS 

remains  sweet  for  an  indefinite  period.  The  souring  of  milk 
is  due  to  the  activities  of  the  so-called  lactic-acid  bacteria. 
They  convert  the  milk  sugar  into  lactic  acid,  which  causes 
the  milk  to  curdle  and  gives  it  a  sour  taste.  As  no  other 
bacteria  can  grow  so  rapidly  in  milk  as  this  organism, 
they  soon  far  outstrip  any  others  which  may  have  gained 
entrance,  and  become  the  predominating  organism.  A  pint 
of  sour  milk  would  contain  about  20,000,000,000  of  these 
minute  cells.  While  such  milk  is  injurious  to  infants,  it 
can  be  consumed  in  large  quantities  by  children  and  adults 
without  any  ill  effects,  while  there  is  some  evidence  that 
at  times  its  use  is  beneficial.  The  nutritive  value  of  sour 
milk  is  very  nearly  equal  to  that  of  sweet  milk. 

Tuberculosis  transmitted  by  milk.  A  great  variety  of 
other  bacteria  are  also  generally  found  in  ordinary  milk. 
Some  of  these  are  present  because  the  cow  is  diseased.  A 
number  of  diseases  may  in  this  manner  be  transmitted  from 
cattle  to  man.  This  is  especially  true  of  tuberculosis,  which 
has  become  prevalent  to  an  alarming  extent  in  dairy  cattle 
in  spite  of  persistent  efforts  to  check  it.  Because  of  the 
almost  equal  prevalence  of  the  same  disease  among  human 
beings,  and  the  slowness  with  which  it  develops  after  enter- 
ing the  human  system,  it  has  been  found  impossible  to 
determine  to  how  great  an  extent  the  prevalence  of  the 
disease  is  to  be  attributed  to  an  infected  milk  supply. 
It  seems  to  be  well  established,  however,  that  the  bacteria 
of  this  disease  may  at  any  time  be  present  in  our  ordinary 
supplies  of  milk  and  be  transmitted  to  human  beings. 

Other  diseases  transmitted  by  milk.  A  number  of  other 
diseases,  such  as  diphtheria,  typhoid,  and  scarlet  fever,  as 
well  as  dysentery  and  intestinal  diseases,  may  also  be  trans- 
mitted by  means  of  milk.  Measles  and  smallpox  are  also 
believed  by  many  to  have  been  carried  by  infected  milk.   The 


BACTEEIA  m  MILK  47 

bacteria  producing  these  diseases  generally  gain  entrance  to 
the  milk  from  infected  persons  who  handle  it  at  the  dairy 
or  during  its  transportation  to  the  consumer.  The  typhoid 
bacteria  may  also  be  introduced  from  the  water  used  to 
wash  cans  or  other  milking  utensils. 

Production  of  pure  milk.    The  requirements,  therefore, 
which  must  be  met  in   producing  and  delivering  a  pure 


Fig.  5.    Model  Stalls 
Plenty  of  light,  and  cement  floor  kept  scrupulously  clean 

and  wholesome  supply  of  milk  are  the  exclusion  of  disease 
bacteria  and  the  lessening  of  the  activity  of  lactic-acid  bac- 
teria so  that  the  milk  shall  reach  the  consumer  before  it  be- 
comes sour.  The  great  concentration  of  population  around 
our  large  cities  has  very  materially  increased  the  difficulties' 
to  be  overcome  by  our  dairymen.  The  milk  delivered  in 
New  York  City,  for  instance,  is  twenty-four  to  thirty-six 
hours  old.  It  must  be  delivered  in  such  condition  that  it 
will  remain  sweet  at  least  twenty-four  hours  longer.    The 


48  PURE  FOODS 

production  of  such  a  milk  supply  requires  great  care  at  the 
dairy  to  prevent  the  entrance  of  bacteria.  The  greatest 
cleanliness  must  be  observed  with  reference  to  the  milking 
rooms,  the  milking  utensils,  the  cattle,  and  the  dairymen. 
As  *dust  generally  carries  bacteria  in  great  numbers,  it  must 
be  excluded  so  far  as  possible.  Plenty  of  light  and  air  must 
be  admitted.  In  the  better  class  of  dairies  a  veterinary 
surgeon  exammes  the  cattle  at  frequent  intervals  to  ascer- 
tain if  they  are  diseased  in  any  way,  and  especially  in  order 
to  make  the  tuberculin  test  by  which  it  is  possible  to  ascer- 
tain if  a  cow  has  contracted  tuberculosis  in  any  form.  The 
water  used  to  wash  milking  utensils  is  tested  to  insure 
its  purity.  Dairymen  having  contagious  diseases  are  not 
allowed  to  remain  at  the  dairy.  To  guard  against  con- 
tamination in  transit  the  milk  at  the  dairy  is  often  put  in 
sterilized  bottles  closed  with  sterilized  caps.  Some  forty 
rules  of  this  kind  have  been  compiled  by  a  large  milk  com- 
pany for  its  dairies,  and  are  enforced  by  an  elaborate  system 
of  inspectors. 

Certified  milk.  When  every  precaution  of  this  kind  is 
taken  to  exclude  disease  bacteria,  and  the  entire  process  is 
supervised  by  a  medical  association,  the  product  is  called 
certified  milk  and  is  sold  at  a  much  higher  price  than 
ordinary  milk.  The  only  test  which  can  be  applied  to  as- 
certain if  a  pure  product  has  been  produced,  is  to  make  a 
count  of  the  number  of  bacteria  present  per  cubic  centi- 
meter. A  limit  of  about  15,000  is  usually  established. 
While  there  is  no  absolute  certainty  that  some  of  the  bac- 
teria present  may  not  be  those  producing  disease,  expe- 
rience proves  that  this  is  very  rarely  the  case,  so  that 
certified  milk  may  be  considered  by  far  the  purest  milk 
sold.  Because  of  its  high  cost  it  is  generally  used  only 
by  invalids  and  children. 


BACTERIA  IN  MILK 


The  use  of  preservatives  in  milk.  A  number  of  methods 
have  been  devised  for  rendering  milk,  produced  under  or- 
dinary conditions,  safe  and  capable  of  remaining  sweet  for 
the  necessary  length  of  time.  A  number  of  chemical  com- 
pounds, known  as  preservatives,  have  been  found  which 
will  prevent  milk  from  souring  if  added  in  very  minute 


Fig.  6.   Model  Milking  Room 

quantities.  As  this  method  has  commonly  been  condemned 
by  health  authorities,  it  has  not  come  into  general  use.  In 
most  cities  dealers  selling  such  milk  are  subject  to  a 
heavy  fine. 

Sterilized  milk.  Heating  the  milk  to  a  sufficiently  high 
temperature  has  been  found  to  kill  the  bacteria.  If  the 
milk  is  heated  to  a  temperature  considerably  above  its  boil- 
ing point,  absolutely  all  bacteria  are  killed ;  and  if  properly 


50  PURE  FOODS 

protected  from  the  entrance  of  bacteria,  such  milk  will  remain 
sweet  indefinitely.  It  is  then  known  as  sterilized  milk.  It  is 
not,  however,  a  suitable  food  for  invalids  and  children,  the 
high  temperature  having  materially  changed  its  properties. 


Fig.  7.    Steam  Sterilizer 

The  milk  bottles  are  loaded  on  small  cars  which  are  run  into  the  sterilizer, 
the  door  bolted  on,  and  steam  introduced 

Pasteurized  milk.  It  has  been  found  that  the  various 
species  of  bacteria  are  not  equally  susceptible  to  the  in- 
fluence of  heat,  so  that  some  are  killed  at  a  much  lower 
temperature  than  is  necessary  for  others.  This  difference 
is  largely  due  to  the  fact  that  some  species  of  bacteria  are 
capable  of  producing  spores  which  are  analogous  to  the 


BACTERIA  IN  MILK 


51 


seeds  of  plants  and  can  resist  drought  and  heat  to  a  con- 
siderable extent.  Under  favorable  conditions  of  temper- 
ature and  moisture  these  spores  are  capable  of  developing 
into  bacteria  actively  growing  and  multiplying.  As  the 
disease-producing  bacteria  which  occur  in  milk  do  not  pro- 
duce spores,  they  are  destroyed  at  a  relatively  low  temper- 
ature.  This  fact  was  discovered  by  the  great  bacteriologist 


Fig.  8.    Filling  Milk  Bottles 
Milk  reservoir  is  covered  to  keep  out  dust,  and  bottles  are  capped  immediately 

Pasteur.  His  name  is  therefore  given  to  the  process  of 
heating  milk  to  a  temperature  just  sufficient  to  destroy 
these  bacteria.  This  is  accomplished  by  heating  the  milk 
for  twenty  minutes  at  165°  F.  or  65°  C.  Such  milk  is 
called  Pasteurized.  It  still  contains  a  small  number  of 
living  bacteria  or  their  spores,  which  develop  and  multiply 
if  the  milk  is  allowed  to  stand  at  room  temperature  for  a 
day  or  two.  It  will  remain  sweet  for  a  much  longer  time 
than  the  unheated  milk,  and  is  a  perfectly  safe  article  of  diet 


52  PURE  FOODS 

because  the  disease  bacteria  which  may  have  been  present 
have  been  killed.  Some  of  the  constituents  have  under- 
gone slight  changes  in  composition,  as  is  evident  from  the 
taste  which  is  not  identical  with  that  of  the  unheated  milk. 
In  this  respect  certified  milk  is  to  be  preferred. 

Advantage  of  Pasteurization.  Pasteurization  is  the  only 
method  of  treatmg  milk  to  render  it  safe  as  a  food,  which 
has  been  found  commercially  feasible.  The  increased  keep- 
ing qualities  of  the  Pasteurized  milk  compensates  for  the 
slight  expense  of  heating  it.  Both  the  dairy  and  domestic 
Pasteurization  of  milk  has  been  very  extensively  employed 
in  recent  years,  so  that  a  large  proportion  of  the  milk  sold 
in  our  large  cities  is  now  Pasteurized.  The  commercial 
Pasteurization  of  milk  often  differs  from  the  scientific 
method  of  carrying  out  this  process  in  that  the  milk  is 
kept  hot  for  a  much  shorter  time  than  twenty  minutes. 
While  the  vitality  and  virulence  of  disease  bacteria  are  un- 
doubtedly very  much  reduced  by  such  a  process,  it  is 
certain  that  they  are  not  killed.  Fortunately  the  normal 
healthy  human  bemg  is  able  to  destroy  great  numbers  of 
disease  bacteria,  but  for  invalids  and  very  young  children 
it  is  advisable  to  Pasteurize  for  twenty  minutes. 

Buddeized  milk  has  been  considerably  used  in  Europe. 
This  process  is  somewhat  similar  to  Pasteurization,  but 
differs  in  that  the  temperature  employed  is  somewhat  lower 
than  50°  C.  or  122°  F.,  and  that  in  addition  a  small  amount 
of  hydrogen  peroxide  is  added.  This  compound  is  similar  to 
water,  but  differs  in  that  it  contains  more  oxygen.  It  is  an 
excellent  disinfectant,  and  when  actmg  as  such  it  decomposes 
into  oxygen  and  water,  leaving  no  other  decomposition  prod- 
uct. During  the  Buddeizing  process  all  the  hydrogen  per- 
oxide added  is  decomposed,  while  the  bacteria  are  destroyed 
quite  as  completely  as  during  the  Pasteurization. 


BACTEKIA  IN  MILK 


53 


Variations  in  the  bacteria  content  of  milk.  The  following 
table  gives  the  number  of  bacteria  found  in  milk  as  sold  in 
New  York  City : 

TABLE  XIII 
Bacteria  in  Milk  sold  in  New  York  City 


Number  per  cubic  centimeter 

Milk  Co.  No.  1  . 

8^,  bottled 

342,000 

Milk  Co.  No.  2  . 

8j^,  bottled 

84,000 

9,500         12,000       42,600 

Milk  Co.  No.  3  . 

8/,  bottled 

84,000 

73,500       179,200 

Milk  Co.  No.  4  . 

8)^,  bottled 

43,000 

Milk  Co.  No.  5  . 

8j^,  bottled 

12,000,000 

6f,  in  bulk 

4,060,000 

39,000,000          53,000,000 

The  very  considerable  variation  in  number  of  bacteria 
present  in  different  samples  of  milk  from  the  same  dairy 
is  shown  by  figures  given  for  Milk  Co.  No.  2  and  No.  3. 

These  analyses  were  made  in  the  fall.  During  the  sum- 
mer the  number  is  much  greater.  This  is  due  to  the  fact 
that  low  temperatures  hinder  the  growth  of  bacteria.  The 
average  number  of  bacteria  in  the  milk  sold  in  New  York 
City  during  the  cold  winter  months  is  about  300,000,  while 
during  the  summer  the  average  is  about  2,500,000.  Even 
though  no  specific  disease  bacteria  can  be  shown  to  be 
present,  it  has  been  found  that  the  consumption,  especially 
by  children,  of  milk  containing  a  large  number  of  bacteria 
is  harmful  and  in  the  case  of  infants  frequently  proves 
fatal.  Although  no  legal  limit  has  been  placed  on  the 
number  of  bacteria  which  may  be  present  in  milk  which  is 
sold  in  cities,  500,000  per  cubic  centimeter  has  been  pro- 
posed as  a  limit  for  this  purpose.  Good  milk  should  con- 
tain a  great  deal  less  than  this  number.  In  order  to  prevent 
the  sale  of  milk  containing  an  excessive  number  of  bacteria, 
the  board  of  health  of  the  city  of  New  York  has  for  a 


54  PURE  FOODS 

good  many  years  enforced  the  rule  that  no  milk  shall  be 
brought  into  the  city  which  is  not  at  or  below  50°  F. 

Influence  of  the  milk  supply  on  the  death  rate  of  children. 
The  influence  of  the  character  of  the  milk  supply  on  the 
death  rate  of  children  is  shown  by  the  results  of  experi- 
ments carried  out  by  Dr.  William  H.  Park  and  Dr.  Emmett 
Holt. 

TABLE  XIV 

Effect  of  Milk  Supply  on  Death  Rate  of  Infants  under 
One  Year  of  Age  during  the  Three  Summer  Months 

Xind  of  milk  Per  cent 

Milk  in  bulk  (store  milk) 20 

Condensed  milk 20 

Bottled  milk 9 

Straus  Station  milk  (Pasteurized) 3 

Certified  milk  or  breast  milk none 

It  is  apparent  that  one  child  in  five  is  sacrificed  by  using 
a  contaminated  milk  supply.  During  the  nine  cool  months 
of  the  year  these  investigators  found  that  the  character  of 
the  milk  used  did  not  affect  the  death  rate  of  the  children, 
undoubtedly  because  the  number  of  bacteria  in  all  grades 
of  milk  during  this  time  of  year  is  very  low. 

Determination  of  the  number  of  bacteria.  As  the  whole- 
someness  of  milk  can  be  judged  from  the  number  of  bacteria 
present,  the  determination  of  this  number  is  very  important. 
Fortunately  the  method  of  counting  bacteria  is  fairly  simple, 
if  the  proper  preparation  is  made.  A  measured  volume  of 
milk  is  placed  on  a  plate  containing  a  sterile  nutrient  me- 
dium, which  is  composed  of  meat  extract  and  peptone  to 
nourish  the  growing  bacteria,  and  gelatin  or  agar-agar  to 
make  a  semisolid  medium  in  which  the  bacteria  will  remain 
fixed.    Each  bacterium  multiplies  rapidly,  forming  a  colony 


BACTERIA  IN  MILK  55 

around  it,  which  soon  becomes  large  enough  to  be  visible 
to  the  eye  alone  or  under  only  very  slight  magnification. 
By  counting  these  spots  or  colonies  the  number  of  bac- 
teria originally  present  in  the  milk  can  be  ascertained.  If 
the  number  of  bacteria  present  in  the  milk  is  large,  a 
definite  amount  of  the  milk  is  diluted  with  a  definite 
amount  of  sterile  water  and  a  portion  of  this  solution  taken 
for  the  test.  When  many  colonies  are  formed  on  a  plate, 
the  colonies  on  only  a  small  portion  of  the  plate  are  counted 
and  the  total  number  estimated.  The  determination  is  at 
best  only  approximate,  as  under  the  conditions  of  incubation 
all  of  the  bacteria  do  not  grow  sufficiently  to  be  counted. 
All  material  and  apparatus  used  must  be  thoroughly  cleaned 
and  sterilized  by  heat  so  as  to  kill  all  organisms  present, 
except  those  in  the  milk  to  be  tested. 

EXPERIMENT 

12.  Bacteria  count.  Sterilization  of  apparatus.  Clean  thoroughly 
100  test  tubes  and  insert  firmly  a  plug  of  cotton  in  each  test  tube. 
Clean  the  Petri  dishes  and  the  1-ccm.  pipettes.  Place  the  pipettes  in 
a  copper  tube  having  a  close-fitting  cap,  or  in  a  large  test  tube 
closed  with  a  plug  of  cotton.  Sterilize  this  apparatus  by  placing  it 
in  an  air  oven  heated  to  1.50°  C.  for  one  hour.  Prepare  sterile  water 
by  nearly  filling  a  250-ccm.  flask  with  distilled  water  and  boiling 
vigorously  for  fifteen  to  twenty  minutes.  Insert  a  plug  of  cotton 
and  allow  to  cool. 

Preparation  of  nutrient  gelatin.  Place  500  gm.  of  lean  beef  in  a 
large  beaker  or  flask  and  add  1000  ccm.  of  distilled  water.  The  meat 
must  be  as  free  as  possible  from  fat  and  chopped  fine  or  run  through 
a  sausage  grinder.  Place  a  piece  of  new  cotton  flannel,  with  the 
wool  side  up,  in  a  large  funnel  and  cover  with  a  layer  of  clean  cotton 
wadding.  Filter  the  meat  infusion  through  the  flannel,  squeezing 
out  the  last  portions.  It  is  advisable  to  place  a  second  smaller  funnel 
containing  the  same  filtering  medium  below  the  first  funnel,  so  that 
the  filtered  solution  from  the  first  funnel  passes  through  the  second, 
thus  giving  a  very  clear  solution.    Allow  the  solution  to  flow  into 


56  PUKE  FOODS 

the  inner  vessel  of  an  agateware  double  boiler  of  at  least  two  quarts' 
capacity.  This  vessel  should  be  weighed  empty  as  well  as  after  receiv- 
ing the  meat  infusion.  Add  an  amount  of  Witte's  peptone  equal  to 
1  per  cent  of  the  weight  of  the  infusion,  and  10  per  cent  of  the  best 
quality  of  sheet  gelatin  (gold  label).  Dissolve  the  peptone  and  gelatin 
by  stirring  with  a  thermometer  and  heating  the  solution,  not  allow- 
ing the  temperature  to  rise  above  60°  C.  For  this  purpose  the  outer 
vessel  only  of  the  double  boiler  is  heated  with  the  Bunsen  burner, 
the  inner  vessel  being  surrounded  by  the  hot  water.  After  the  gel- 
atin is  dissolved  the  water  in  the  outer  vessel  is  brought  to  a  boil 
and  kept  boiling  for  thirty  minutes,  the  inner  vessel  being  covered. 

Adjusting  the  acidity.  After  the  boiling  has  continued  for  twenty 
minutes  withdraw  5  ccm.  of  the  solution  with  a  pipette  and  place  in 
a  porcelain  dish  or  casserole.  Add  45  ccm.  of  distilled  water  and  boil 
for  one  minute  over  the  Bunsen-burner  flame.  Add  1  ccm.  of  phenol- 
phthalein  solution  ^  and  titrate  while  hot  (preferably  while  boiling) 
with  N/20  caustic  soda.^  Add  the  soda  solution  until  within  a  drop 
or  two  of  the  end  point  (a  faint  pink  coloration).  Cool  by  standing 
the  dish  in  cold  water,  and  if  a  distinct  pink  color  does  not  develop, 
add  the  soda  solution  drop  by  drop  until  the  end  point  is  reached. 

So  much  of  the  acid  in  the  solution  must  be  now  neutralized  that 
the  amount  of  acid  remaining  in  1000  gm.  will  neutralize  10  ccm.  of 
normal  caustic-soda  solution.  The  calculation  of  the  amount  of  soda 
to  be  added  is  made  as  follows  :  If  the  5-ccm.  portion  titrated  required 
4^  ccm.  of  the  N/20  soda  solution,  and  the  weight  of  the  solution  is 
950  gm.,  the  entire  solution  will  require  855  ccm.  of  the  N/20  soda, 
or  42.7  ccm.  of  normal  soda.  As  the  acid  equivalent  to  10  ccm.  of 
normal  soda  solution  must  be  left  free,  32.7  ccm.  of  normal  soda 
solution  is  added. 

To  coagulate  finely  suspended  matter  so  that  the  solution  may  be 
filtered  clear,  the  white  of  an  egg  is  added  at  this  point.  The  solution 

1  This  solution  is  prepared  by  dissolving  one  tenth  of  a  gram  of  the  crystals 
in  100  ccm.  of  95  per  cent  alcohol. 

2  A  normal  solution  of  caustic  soda  contains  40  gm.  of  sodium  hydroxide 
dissolved  in  enough  water  to  make  1000  ccm.  As  even  the  poorest  caustic  soda 
generally  contains  about  90  per  cent  of  sodium  hydroxide,  about  44  gm. 
must  be  taken.  A  twentieth  normal  solution  (N/20)  is  made  by  diluting 
50  ccm.  of  the  normal  solution  to  1000  ccm.  with  distilled  water.  For  accurate 
methods  of  making  these  solutions,  see  the  author's  textbook  on  "  Quantitative 
Chemical  Analysis." 


BACTERIA  IN  MILK  57 

is  cooled  to  60°-70°  C.  by  immersing  the  containing  vessel  in  cold 
water,  and  the  white  of  an  egg  added  with  stirring ;  it  is  then  heated 
in  the  double  boiler  and  finally  boiled  for  two  minutes  over  the 
free  flame,  with  constant  stirring.  Weigh  and  add  distilled  water 
to  make  up  for  loss  by  evaporation.  Take  out  5  ccm.  and  titrate  with 
N/20  sodium  hydroxide  and  calculate  the  acidity  as  before.  If  the 
acidity  per  1000  gm.  is  less  than  8  ccm.  or  more  than  12  ccm.  of  nor- 
mal acid,  acid  or  alkali  should  be  added  to  bring  the  acidity  to  the 
standard  1  per  cent.  Take  out  another  5-ccm.  portion  and  titrate  a 
third  time  to  ascertain  if  the  adjustment  of  the  acidity  has  been 
correctly  carried  out. 

Sterilization  of  the  culture  medium.  Filter  the  solution  again  through 
absorbent  cotton  and  cotton  flannel,  passing  the  filtrate  through 
the  filter  until  clear.  The  nutrient  gelatin  must  now  be  measured 
off  in  10-ccm.  portions  into  the  sterilized  test  tubes  closed  with 
cotton  plugs.  For  this  purpose  a  glass  tube  graduated  every  10  ccm. 
is  convenient.  The  cotton  plug  is  removed  from  a  sterilized  test 
tube  and  held  between  the  first  and  second  fingers,  and  again  in- 
serted into  the  test  tube  as  soon  as  the  10-ccm.  portion  of  gelatin 
has  been  added.  The  gelatin  should  not  be  allowed  to  touch  the 
upper  portion  of  the  test  tube,  which  is  set  aside  in  an  upright  posi- 
tion to  cool.  When  all  of  the  gelatin  has  been  measured  out  into 
test  tubes,  it  is  sterilized  by  heating  for  five  minutes  in  an  autoclave 
at  120°  C,  which  is  the  temperature  of  steam  at  15  pounds'  pressure. 
The  tubes  of  gelatin  must  be  kept  in  an  ice  chest.  If  the  gelatin  has 
not  been  completely  sterilized,  colonies  will  make  their  appearance 
in  a  few  days. 

The  gelatin  may  also  be  sterilized  by  heating  in  steam  for  twenty 
minutes  for  three  successive  days,  being  kept  in  the  ice  chest  when 
not  being  heated. 

Count  of  bacteria.  To  make  the  count  of  bacteria  in  water  or 
milk,  the  sample  must  be  taken  in  a  sterilized  glass-stoppered  bottle. 
It  is  advisable  before  sterilization  to  cover  the  stopper  with  tin  foil 
to  prevent  entrance  of  bacteria  with  the  dust  from  the  air ;  1  ccm.  is 
withdrawn  ^  with  a  sterilized  pipette  and  transferred  to  a  sterilized  test 
tube  and  9  ccm.  of  sterilized  water  added.  This  gives  a  dilution  of  1 
to  10.    By  diluting  this  solution  in  the  same  manner  a  dilution  of 

1  When  bottled  milk  is  being  tested,  the  bottle  is  thoroughly  shaken,  the 
cap  reinoved,  and  the  1  ccm.  portion  withdrawn. 


58 


PURE  FOODS 


1-100  is  obtained.  Most  samples  of  milk  must  be  diluted  again, 
giving  1-1000.  Very  impure  milks  require  still  another  dilution.  A 
clean  pipette  must  be  used  for  each  dilution.  To  one  of  the  sterilized 
Petri  dishes  1  ccm.  of  the  1-100  dilution  is  transferred,  and  to  the 
second  dish  1  ccm.  of  the  1-1000  dilution.    Tubes  of  the  nutrient 


Fig.  9.    Plate  Cultures  of  Bacteria 

Each  spot  was  produced  by  a  single  bacteria.    The  upper  plate  contains 

sterilized  milk,  the  left-hand  plate  certified  milk,  and  the  right-hand  plate 

ordinary  milk 


gelatin  are  melted  by  placing  in  warm  water,  the  plug  of  cotton 
removed,  the  open  end  of  the  test  tube  sterilized  by  passing  it  through 
the  flame  of  a  Bunsen  burner,  and  the  gelatin  poured  into  the  Petri 
dishes.  The  covers  are  raised  only  when  pouring  in  water  or  gelatin 
so  as  to  prevent  the  entrance  of  bacteria  from  atmospheric  dust.  The 
milk  and  nutrient  gelatin  are  mixed  by  slightly  tilting  the  dish,  so 


BACTERIA  IN  MILK  59 

that  the  contents  flow  from  one  side  to  the  other.  The  dish  is  then 
placed  in  a  horizontal  position  in  a  thermostat  or  refrigerator  kept  at 
about  20°  C.  After  forty-eight  hours  the  number  of  colonies  on  the 
plate  are  counted.  If  the  number  is  not  over  200,  the  total  number 
may  be  counted.  If  the  number  is  large,  some  counting  device  must 
be  employed.  This  generally  consists  of  a  plate  marked  off  in  sections 
or  other  divisions,  in  such  a  manner  that  the  total  number  may  be 
counted ;  the  average  number  of  colonies  per  division  is  then  ob- 
tained by  counting  the  number  of  colonies  in  several  divisions,  so 
as  to  obtain  a  fair  average  of  the  number  per  division.  Small  specks 
of  dust  must  not  be  mistaken  for  colonies  which  are  circular  in 
shape.  The  count  must  generally  be  made  with  a  small  magnifying 
lens.  When  the  colonies  are  small  it  is  sometimes  advisable  to 
allow  the  sample  to  incubate  for  seventy-two  hours.  This  fact  should 
be  stated,  however,  in  reporting  the  analysis.  The  best  results  are 
generally  obtained  by  counting  the  colonies  on  plates  containing 
about  200. 

Preparation  of  nutrient  agar-agar.  When  this  medium  is  prepared 
the  meat  is  soaked  in  one  half  the  quantity  of  water;  that  is,  500  ccm. 
Fifteen  grams  of  thread  agar  are  dissolved  in  500  ccm.  of  water  by 
boiling  for  one-half  hour.  The  amount  of  water  lost  is  then  restored 
and  the  infusion  allowed  to  cool  to  about  60°  C.  The  remaining  opera- 
tions are  identical  with  those  used  in  preparing  gelatin,  except  that 
2  per  cent  of  Witte's  peptone  is  dissolved  in  the  filtered  meat  in- 
fusion, after  which  the  agar  is  added  to  the  meat  infusion,  care 
being  taken  to  keep  the  temperature  below  60°  C. 

The  samples  of  milk  are  plated  as  described  for  gelatin.  It  is 
necessary,  however,  to  heat  the  agar  to  a  higher  temperature  in  order 
to  melt  it.  It  should  be  cooled  to  about  40°  C.  before  pouring  on  the 
plate.  The  plates  are  incubated  at  body  temperature  (37^°-40°  C.) 
for  forty-eight  hours.  The  number  of  colonies  obtained  is  usually 
higher  than  with  gelatin.  It  is  advisable  to  use  porous  earthenware 
covers  with  agar  to  prevent  the  spreading  of  colonies  by  the  conden- 
sation of  water. 


CHAPTER  VI 
FATS  AND  OILS 

Importance  of  fats  in  the  diet.  Fats  and  oils  constitute 
one  of  the  most  important  constituents  of  our  food.  From 
one  eighth  to  one  third  of  the  total  amount  of  food  ordi- 
narily taken  is  fat  or  oil.  As  the  energy  derived  from  this 
class  of  foods  is  more  than  double  that  obtained  from  the 
same  weight  of  the  other  food  constituents,  it  is  evident 
that  fats  and  oils  furnish  fully  half  the  energy  obtained 
by  human  beings  from  their  food.  This  fact  has  been 
popularly  recognized  so  long  that  the  word  "  fat "  has  be- 
come synonymous  with  "  rich  "  or  "  superabundant."  Fats 
also  exert  a  beneficial  influence  on  the  digestive  process,  so 
that  a  diet  without  fat  is  dry  and  unpalatable. 

Percentage  of  fats  in  foods.  Fats  are  very  seldom  con- 
sumed in  the  pure  state,  but  are  generally  combined  or 
blended  with  other  foods.  A  large  proportion  of  foods  in 
their  natural  state  contain  an  appreciable  proportion  of  fat. 
In  fact,  all  of  the  fats  and  oils  used  for  food  have  been 
separated  from  the  other  constituents  with  which  they  are 
naturally  blended. 

Vegetables  and  fruits  contain  very  little  fat.  Bread  and 
other  cereal  products  and  some  kinds  of  fish  contain  only 
small  amounts.  For  this  reason  the  addition  of  butter  or 
salad  oil  renders  these  foods  more  palatable  and  nutritious. 
Most  meats,  as  well  as  a  great  many  nuts  and  other  seeds, 
contain  a  large  proportion  of  fat.  The  following  table  gives 
the  percentage  of  fat  present  in  a  number  of  common  foods. 


FATS  AND  OILS  61 

TABLE  XV 

Percentage  of  Fats  in  Ordinary  Foods 

Per  cent  Per  cent 

Sirloin  steak 17  Coconut 50 

Roast  beef 28  Chocolate 50 

Leg  of  lamb 13  Oatmeal 7 

Ham 40  Bread 1^ 

Bacon 64  Vegetables 1 

Salt  pork 85  Fruits \ 

Cheese 33  Butter S5 

Salmon 17  Olive  and  salad  oils  ....  100 

Bluefish 1 

Chemical  composition  of  fats.  Fats  are  composed  of  the 
same  chemical  elements  as  carbohydrates;  that  is,  carbon, 
hydrogen,  and  oxygen,  although  the  proportion  of  oxygen 
is  very  much  less  than  in  carbohydrates.  For  this  reason 
more  than  double  the  arnount  of  heat  or  energy  is  given 
out  during  their  combustion.  Fats  are  also  much  more 
complex  in  structure.  If  an  oil  is  kept  at  a  low  temper- 
ature for  some  time,  it  separates  into  two  constituents,  one 
of  which  is  solid,  and  the  other  liquid.  The  solid  con- 
stituent can  be  separated  by  filtration  from  the  liquid  fat 
or  oil.  If  the  two  constituents  are  allowed  to  remain 
together  and  the  mixture  warmed,  the  solid  melts  so  that 
the  oil  resumes  its  original  appearance.  Its  properties  are 
not  quite  the  same  as  before,  however.  It  is  a  well-known 
fact  that  olive  oil  which  has  been  frozen  will  not  make  as 
good  a  salad  dressing  as  the  unfrozen  oil.  In  a  similar 
manner  a  solid  fat  may  be  heated  to  a  point  where  only  a 
portion  is  converted  into  an  oil.  The  solid  portion  may  be 
separated  by  filtration  and  is  known  as  stearhi.  Both  solid 
fats  like  tallow,  and  oils  like  cottonseed  oil,  are  converted 
on  a  commercial  scale  into  more  desirable  products  in  this 
manner.   From  the  tallow  a  hard  solid  (stearin)  and  an  oil  is 


62  PURE  FOODS 

obtained.  By  cooling  the  cottonseed  oil,  cottonseed  stearin 
may  be  separated  out  and  the  remaining  oil  will  remain 
liquid  at  much  lower  temperatures  than  the  original  oil. 

Glycerin  and  acids  found  in  fats.  It  is  possible  to  carry 
the  decomposition  of  both  the  stearin  and  the  oil  still 
further.  There  are  a  number  of  methods  of  carrying  out 
this  decomposition,  but  by  each  there  are  obtained  as  in- 
variable constituents  both  glycerin  and  one  or  more  of  the 
so-called  fatty  acids.  Experiments  of  this  kind  show  that 
almost  all  animal  and  vegetable  fats  and  oils  are  composed 
of  glycerin  in  combmation  with  one  or  more  of  the  fatty 
acids,  most  natural  fats  and  oils  containing  several  acids. 
Some  of  these  acids  form  fats  which  are  liquid  at  ordinary 
temperatures,  and  are  therefore  called  oils,  while  others 
form  solid  fats.  Oleic  acid  is  the  most  common  of  the  fatt}" 
acids  which  produce  oils,  while^  stearic  and  palmitic  acids 
constitute  the  bulk  of  solid  fats.  A  fat  like  lard,  which 
melts  easily,  contains  a  large  proportion  of  oleic  acid,  while 
beef  and  mutton  tallow,  which  melt  at  a  much  higher  tem- 
perature, contain  a  large  proportion  of  stearic  acid.  These 
acids  are  always  combined  with  glycerin  in  the  natural 
state  of  the  fats  or  oils.  An  oil  does  not  contain  free  oleic 
acid.  It  contains  olein,  which  is  the  name  given  to  the 
compound  formed  when  oleic  acid  combines  with  glycerin. 
Similarly,  tallow  contains  palmatin  and  stearin ;  that  is, 
compounds  of  palmitic  and  stearic  acids  with  glycerin.  The 
percentage  of  glycerin  is  quite  small,  averaging  8  per  cent 
for  the  common  fats. 

Decomposition  of  fats.  As  the  glycerin  and  the  fatty  acids 
are  not  very  firmly  combined,  most  fats  are  quite  easily  de- 
composed. Heating  with  steam  and  action  of  bacteria  or 
of  digestive  fluids  are  some  of  the  common  ways  in  which 
fats  are  decomposed.   The  characteristic  odor  emitted  when 


FATS  AND  OILS 


63 


foods  are  fried  with  fat  of  any  kind  is  produced  by  acrolein, 
a  product  of  the  decomposition  of  glycerin.  The  disagree- 
able odor  of  rancid  butter  is  due  largely  to  the  liberation 
of  one  of  its  fatty  acids  known  as  butyric  acid,  which  has 
a  very  characteristic  and  disagreeable  odor.  In  the  process 
of  making  soap,  fats  are  decomposed  by  means  of  caustic 
soda  or  potash,  commonly  known  as  soda  lye  or  potash  lye. 
In  this  process  the  fatty  acid  combines  with  the  soda  or 
the  potash  and  forms  soap.  When  this  reaction  is  brought 
about,  the  fat  is  said  to  be  saponified.  The  glycerin  is  set 
free  and  may  be  allowed  to  remain  in  the  soap,  or  may  be 
separated  and  purified  to  be  used  for  pharmaceutical  pur- 
poses or  in  the  arts. 

The  fatty  acids.    The  following  table  gives  the  names 
and  chemical  formulas  of  the  fatty  acids  found  in  ordinary 


TABLE  XVI 
Acids  found  in  Fats  and  Oils 


Name 

Chemical 
formula 

Where  found 

Butyric     . 
Caproic     . 
Caprylic    . 
Capric  .    . 
Laurie  .    . 

C.H^O, 

C10H20O2 

^12^24^2 

Butter 

Butter,  coconut  oil 
Butter,  coconut  oil 
Butter,  coconut  oil 
Coconut  oil 

Myristic    . 
Palmitic    . 
Stearic  .    . 
Arachidic 
Behenic     . 

Ci6H3,0, 

C,3H3A 
C20H40O2 
^22^44^2 

Coconut  oil 

Nearly  all  oils  and  fats 
Nearly  all  oils  and  fats 
Peanut  oil,  coco  butter 
Oil  of  ben 

Lignoceric 
Oleic     .    . 
Rapic    .    . 
Linolic  .    . 

^24^48^2 

^18^34^2 
C18H34O2 
^1 8^32^2 

Peanut 

Nearly  all  oils  and  fats 
Rape  mustard 
Cottonseed,  corn,  almond, 

peanut,  olive 

Erucic  .    . 

^22^42^2 

Rape  mustard 

64  PUEE  FOODS 

fats  and  oils.  The  chemical  formulas  show  that  they  are 
composed  of  three  elements  only  ;  that  is,  carbon,  hydrogen, 
and  oxygen,  and  that  the  amount  of  oxygen  is  quite  small. 

The  flavor  of  oils.  In  addition  to  the  fatty  acids  and 
glycerin,  there  are  present  in  oils  small  quantities  of  other 
chemical  compounds  which  give  distinctive  flavors  or  odors. 
Some  oils  contain  constituents  which  are  either  poisonous, 
like  croton  oil,  or  have  a  disagreeable  taste  or  smell,  and  for 
this  reason  cannot  be  used  for  human  food.  Others  have 
constituents  which  possess  medicinal  properties,  such  as 
castor  oil  and  cod-liver  oil.  The  oils  which  do  not  contain 
deleterious  or  medicinal  constituents  may  be  used  as  foods. 
The  following  vegetable  oils  are  of  this  character:  almond 
oil,  coconut  oil,  cottonseed  oil,  corn  oil,  hazelnut  oil,  olive 
oil,  peanut  oil,  rape  oil,  sesame  oil,  sunflower  oil,  and  poppy- 
seed  oil.  All  of  these  oils  will  not  be  used  to  any  great 
extent  in  a  given  country,  as  the  people  will  generally  use 
most  largely  the  oils  which  can  be  most  easily  produced 
in  that  country,  although  taste  and  cost  will  influence  con- 
sumption. In  nutritive  value  there  is  very  little  difference 
between  these  oils.  There  seems  to  be  a  considerable  dif- 
ference in  digestibility,  which  is  apparently  dependent  on 
the  fatty  acids  which  constitute  the  oil.  The  oils  most 
largely  used  in  the  United  States  for  food  are  olive  and 
cottonseed. 

Coconut  oil.  This  oil  resembles  butter  fat  more  than  any 
other  natural  fat  or  oil,  and  has  therefore  been  largely  used 
in  making  artificial  butter.  It  is  made  from  the  ordinary 
coconut  by  pressing  the  flesh  until  the  oil  flows  out. 

Cottonseed  oil.  This  oil  is  most  largely  used  for  food 
purposes  in  the  United  States,  and  has  also  displaced  the  use 
of  other  oils  to  a  great  extent  in  Europe.  The  enormous 
amount  of  3,200,000  barrels  containing  50  gallons  each 


EATS  AND  OILS 


65 


are  produced  yearly.  Between  2,000,000  and  2,500,000 
barrels,  or  125,000,000  gallons,  of  this  amount  are  used 
for  food.  If  equally  divided,  this  would  give  each  man, 
woman,  and  child  in  the  United  States  about  a  gallon 
and  a  half,  which  is  therefore  the  average  per  capita 
amount  of  this  oil  consumed  each  year  by  the  people  of 
the  United  States.  The  following  table  gives  the  purposes 
for  which  the  cottonseed  oil  is  used : 

TABLE  XVII 
Consumption  of  Cottonseed  Oil  for  the  Year  1905 


Domestic 

Foreign 

Barrels 

Barrels 

280,000 

360,000 

170,000 

16,000 

1,000,000 

100,000 

10,000 

250,000 

50,000 

30,000 

450,000 

200,000 

145,000 

44,000 

Salad  oil      ... 
Cooking  and  bakin< 
Compound  lard  .    , 
Oleomargarine    .    , 
Packing  sardines 
Soap  making  .    . 
Other  purposes    .    . 


The  oil  press.  The  process  of  extracting  the  oil  from  the 
cottonseed  and  refining  it  until  it  is  suitable  for  food  is 
quite  complicated.  The  cotton  gin,  which  separates  the 
seed  from  the  fiber,  to  be  used  as  cotton,  leaves  a  consid- 
erable amount  of  short  fiber  known  as  ''  linters."  In  the 
oil  mill  the  linters  are  first  removed,  after  which  the  seeds 
are  chopped  up  by  rapidly  revolving  knives  and  passed 
over  shaking  screens,  which  shake  out  the  meats,  the  hulls 
being  passed  on  to  the  hull  pile.  The  meats  containing 
from  30  to  36  per  cent  of  oil  are  first  passed  between 
heavy  rolls  and  then  cooked  in  steam-jacketed  kettles  and 
pressed  in   hydraulic   presses  between  camel's-hair  press 


66  PUEE  FOODS 

cloths.  About  85  per  cent  of  the  oil  flows  out  through 
the  press  cloth.  The  cake  remaming  m  the  press  contains 
about  7  per  cent  of  oil  and  38  per  cent  of  protein,  and  is 
largely  used  as  a  cattle  food. 

The  refining  of  oil.  The  crude  oil  thus  obtained  must  be 
refined.  For  this  purpose  it  is  heated  and  agitated  in  large 
tanks  with  dilute  caustic  soda,  which  combines  with  the 
free  fatty  acids  in  the  oil  and  also  removes  resinous  color- 
ing matters.  After  allowing  the  impurities  to  settle,  the 
clear  yellow  oil  is  drawn  off,  dried,  and  filtered.  This  is 
known  as  "  Prime  Summer  Yellow  "  cottonseed  oil.  It  is 
further  refined  by  filtration  through  Fuller's  earth  and 
subjected  to  a  deodorizing  process.  This  oil  is  sold  under 
various  brands  for  cooking  purposes. 

Lard  substitutes.  Large  quantities  of  this  oil  are  used 
for  the  preparation  of  "snowdrift,"  cottolene,  and  other 
substitutes  for  lard.  These  products  are  made  by  melting 
up  in  the  heated  oil  15  to  20  per  cent  of  oleostearin.  The 
melted  fat  is  then  cooled  suddenly  by  passing  over  artifi- 
cially cooled  rolls.  It  then  very  closely  resembles  lard  in 
appearance  and  properties. 

Salad  oil  is  prepared  by  chilling  the  highly  refined  cotton- 
seed oil  until  the  "  cottonseed  stearin "  crystallizes  out. 
This  so-called  "  stearin "  is,  in  fact,  palmitin.  The  oil  is 
pressed  out  of  this  semisolid  mass.  Cottonseed  oil  is  used 
very  largely  for  frying,  since  it  will  stand  a  higher  tem- 
perature without  smoking  than  lard  or  butter.  Large 
quantities  are  also  used  in  making  artificial  butter. 

Olive  oil.  This  is  the  most  highly  prized  oil  for  table 
use.  This  preference  is  largely  due  to  its  very  agreeable 
flavor.  It  has  been  used  as  a  food  from  the  very  earliest 
times  of  which  we  have  any  historic  record.  It  is  no  more 
nutritious  than  the  other  edible  oils.   It  is  about  five  times 


FATS  AND  OILS  67 

as  expensive,  however,  as  cottonseed  oil.  On  account  of 
its  high  price  it  has  been  very  largely  adulterated  by  the 
admixture  or  substitution  of  cheaper  oils.  If  not  more 
than  20  to  30  per  cent  of  a  foreign  oil  is  present,  it  is 
almost  impossible  to  distinguish  by  taste  between  the  pure 
and  the  adulterated  oil.  In  the  United  States  cottonseed 
oil  has  been  most  largely  used  as  the  adulterant,  while 
in  Europe  sesame  and  peanut  oils  have  been  largely  used, 
while  castor  oil,  lard  oil,  fish  oil,  and  even  petroleum  have 
been  found  as  adulterants.  Olive  oil  contains  olein  and 
palmitin,  but  "very  little  stearin.  From  3  to  20  per  cent 
of  palmitin  is  present. 

Various  grades  of  olive  oil.  The  greatest  care  is  taken  in 
the  preparation  of  olive  oil.  The  olives  must  be  hand  picked. 
If  they  are  shaken  down  and  bruised,  the  oil  is  not  of  so 
fine  a  flavor  as  when  made  from  fruit  whose  flesh  is  entirely 
unbroken.  The  olives  should  be  cold-pressed  to  produce 
the  finest  oil,  which  is  called  "  virgin  oil."  If  the  olives 
are  heated,  the  oil  begins  to  decompose  so  that  some  of 
the  acid  is  separated  from  the  glycerin,  which  injures  the 
flavor.  If  perfect  olives  are  cold-pressed,  a  perfectly  neutral 
oil  is  produced.  The  residue  from  the  first  cold-pressing 
is  heated  and  again  pressed,  thus  producing  an  additional 
quantity  of  oil,  which  is  of  inferior  quality  to  the  virgin 
oil.  This  oil  may  be  refined  by  a  process  similar  to  that 
used  for  cottonseed  oil,  and  is  then  suitable  for  use  as  a 
food,  but  it  is  not  of  so  fine  a  quality  as  the  virgin  oil,  which 
requires  little  or  no  refining.  A  third  quality  of  oil  may 
be  obtained  by  treating  the  residue  from  the  hot  presses 
with  carbon  disulphide  or  petroleum  ether.  These  liquids 
dissolve  the  oil  and  are  then  distilled  off  to  be  used  again. 
The  oil  obtained  in  this  manner  should  not  be  used  as  a 
food,  but  is  suitable  for  soap  making.   If  too  great  pressure 


68  PUEE  FOODS 

is  used  in  obtaining  olive  oil,  the  hard  kernel  of  the  fruit  is 
crushed  and  an  oil  pressed  out  of  the  kernel  which  is  similar 
to  the  oil  from  the  flesh  of  the  fruit  but  distinctly  inferior. 
Other  food  oils.  By  similar  processes  the  oil  is  pressed 
out  of  various  seeds  and  nuts,  such  as  hazelnut,  peanut, 
rapeseed,  sesame,  sunflower  seeds,  etc.  Some  of  these  oils 
are  very  palatable  and  easily  digested.  Their  nutritive 
value  is  very  nearly  the  same  as  that  of  the  cottonseed 
and  olive  oil.  The  preference  for  one  or  the  other  of  these 
oils  is  largely  a  matter  of  flavor. 

EXPERIMENTS 

13.  Production  of  stearin.  Place  a  sample  of  cottonseed  or  olive 
oil  in  ice  and  salt.  For  this  purpose  the  oil  may  be  placed  in  a  bottle 
or  test  tube.  When  thoroughly  cooled,  a  white  solid  will  separate 
out.  This  is  the  so-called  cottonseed-oil  or  olive-oil  stearin.  It 
may  be  separated  from  the  liquid  portion  by  squeezing  through 
cloth  of  suitable  fineness.  If  allowed  to  become  warm,  the  stearin 
again  goes  into  solution  in  the  oil. 

14.  Determination  of  acidity.  As  the  glycerin  is  not  very  firmly 
combined  with  the  fatty  acid,  the  latter  is  set  free  when  the  fat  or 
oil  is  heated  and  becomes  rancid,  or  even  when  allowed  to  stand  for 
some  time.  The  amount  of  free  acid  may  therefore  be  taken  as  an 
index  of  the  method  of  production  or  refinement,  age  or  condition 
of  the  fat  or  oil,  the  best  oils  being  nearly  neutral. 

The  determination  is  carried  out  as  follows :  From  1  to  10  gm. 
of  the  fat  or  oil,  depending  upon  the  amount  of  fatty  acid  present, 
are  weighed  out  and  transferred  to  a  small  flask.  The  fat  is  dis- 
solved in  50  ccm.  of  neutral  alcohol  or  the  same  quantity  of  a 
mixture  of  equal  parts  of  alcohol  and  ether,  if  the  fat  does  not 
dissolve  in  alcohol  alone.  One  drop  of  phenolphthalein  is  added  and 
then  fifth-normal  caustic   soda^  introduced  drop  by  drop  from  a 

1  For  the  preparation  of  this  solution  see  p.  190.  More  accumte  results 
may  be  obtained  by  the  use  of  an  alcoholic  solution  of  caustic  potash.  For 
the  preparation  of  this  solution  see  the  author's  text  on  "Quantitative 
Chemical  Analysis,"  4th  ed.,  p.  437. 


FATS  AND  OILS  •      69 

burette  with  constant  and  vigorous  shaking  until  a  pink  color  is 
produced.  The  first  appearance  of  the  pink  color  is  taken  as  the 
end  point.  It  may  fade  on  standing  a  few  minutes,  but  this  is  due 
to  saponification  of  the  neutral  glycerides  by  the  excess  of  alkali. 

The  result  is  expressed  in  per  cent  of  oleic  acid.  One  ccm.  fifth- 
normal  alkali  is  equal  to  0.0564  gm,  of  oleic  acid.  If  3  ccm.  of 
the  alkali  is  required  to  titrate  the  free  acid  in  2  gm.  of  fat,  the 

.     /0.0564  X  3  X  100  \ 

percentage  of  free  acid  is  8.46  I =  8.46  I. 

When  carrying  out  this  determination  on  butter,  the  fat  must  be 
melted  at  the  lowest  j)ossible  temperature  and  the  water  and  casein 
allowed  to  settle  out.  The  clear  fat  is  drawn  off  and  used  in  making 
the  test  for  acidity.  If  borax  or  boric  acid  has  been  added  as  a 
preservative,  it  will  be  present  in  the  water,  which  may  be  tested  for 
the  preservative  in  the  manner  given  on  page  41. 

15.  Soap  making.  In  the  process  of  making  soap  the  fatty  acids 
are  separated  from  the  glycerin  by  boiling  with  caustic  soda  or  potash, 
the  soap  being  the  compound  formed  by  the  union  of  the  alkali  with 
the  fatty  acid.  This  process  may  be  carried  out  as  follows :  15  gm. 
of  solid  caustic  soda  are  dissolved  in  120  ccm.  of  water.  One  half 
of  the  solution  is  poured  into  a  suitable  vessel,  an  equal  volume  of 
water  and  50  gm.  of  tallow,  cottonseed,  castor,  or  other  oil  added. 
The  mixture  is  brought  to  a  boil  and  kept  boiling  for  about  half  ail 
hour,  water  being  added  to  replace  that  lost  by  evaporation.  If  tallow 
has  been  used,  it  will  be  necessary  to  add  the  remainder  of  the 
caustic  solution  and  continue  the  boiling  for  another  hour,  finally 
allowing  the  liquid  to  become  more  concentrated.  About  20  gm.  of 
salt  are  then  added  and  the  solution  boiled  for  a  few  minutes 
and  then  allowed  to  cool.  The  soap  rises  to  the  top  and  solidifies 
to  a  hard  cake.  The  glycerin  and  excess  of  caustic  are  present  in 
the  brine. 

16.  Preparation  of  stearic  acid.  A  portion  of  the  soap  made  in  the 
preceding  experiment  is  dissolved  by  heating  with  soft  or  distilled 
water.  If  the  saponification  or  conversion  of  the  tallow  or  oil  into 
soap  has  been  complete,  a  clear  solution  will  be  obtained. 

Dilute  hydrochloric  acid  is  added  to  this  solution  until  it  is  de- 
cidedly acid.  The  liquid  will  become  turbid  on  account  of  the  sepa- 
ration of  the  free  fatty  acids,  mainly  stearic  and  oleic.  On  warming 
the  solution  and  allowing  it  to  stand  for  some  time,  the  fatty  acids 


70  PUKE  FOODS 

will  collect  as  an  oily  layer  on  top  of  the  solution  and  will  solidify 
on  cooling.  This  white  fatty  substance  is  what  is  sold  as  stearic  acid. 
17.  Test  for  cottonseed  oil.  As  cottonseed  oil  is  very  cheap  as 
well  as  quite  palatable,  it  is  very  apt  to  be  used  as  an  adulterant  of 
more  expensive  fats  and  oils.  Fortunately  it  can  be  easily  tested 
for.  For  this  purpose  a  solution  known  as  Halphen's.  reagent  is 
used.  It  is  made  by  dissolving  1  gm.  of  sulphur  in  100  ccm.  of 
carbon  disulphide  and  adding  an  equal  volume  of  amyl  alcohol. 
Equal  volumes  of  this  reagent  and  the  oil  to  be  tested  are  mixed  in 
a  test  tube  and  heated  by  immersion  in  boiling  water,  or,  still  better, 
boiling  saturated  brine.  After  heating  for  about  fifteen  minutes  a 
red  color  is  developed  if  cottonseed  oil  is  present.  The  delicacy  of 
the  test  may  be  studied  by  applying  it  to  samples  of  oil  containing 
known  amounts  of  cottonseed  oil.  For  this  purpose  10,  20,  and  50 
per  cent  of  cottonseed  oil  may  be  added  to  olive,  lard,  or  other  suit- 
able oil  and  the  test  applied.  It  will  be  observed  that  the  depth  of  the 
color  will  give  some  idea  of  the  amount  of  cottonseed  oil  present. 


CHAPTER   VII 

BUTTER   AND   ITS   SUBSTITUTES 

Production  of  butter.  Butter  is  the  product  obtained  by 
a  process  having  for  its  object  the  separation  of  the  fat  of 
milk  in  a  relatively  pure  form.  The  first  step  in  this  process 
consists  in  the  production  of  cream.  While  milk  contains 
only  about  3i-  per  cent  of  fat,  cream  may  contain  as  much 
as  40  per  cent,  the  remainder  being  casein,  which  is  the 
protein  of  milk  and  water.  The  fat  is  present  as  minute 
globules,  which  are  surrounded  by  a  layer  of  casein.  These 
globules  are  so  small  and  light  that  they  float  in  the  whey 
of  the  milk.  When  the  cream  has  become  acid  by  the  action 
of  bacteria,  it  is  subjected  to  a  vigorous  agitation  known 
as  churning,  by  which  the  casein  is  separated  from  the  fat, 
which  then  unites  to  form  large  masses  of  butter,  the 
composition  of  which  is  given  in  the  following  table: 

TABLE  XVIII 
Composition  of  Butter 

Per  cent  Per  cent 

Fat 80  to  85  average  84 

Water 7  to  16  average  12.8 

Salt 2  to  3  average    2.0 

Sugar 0.3  to  0.5  average    0.4 

Protein       0.6 

Coloring  matter 

As  is  shown  by  the  table,  butter  is  not  100  per  cent  fat, 
but  still  contains  some  water,  casein,  sugar,  and  salt  as 
ordinarily  consumed. 

71 


72  PUEE  FOODS 

Butter  fat.  The  butter  fat  could  easily  be  separated  in 
pure  condition,  but  it  would  not  be  as  palatable  an  article 
of  food  as  the  butter  to  which  we  are  accustomed.  The 
fat,  however,  is  the  essential  constituent  of  butter.  It  is 
to  obtain  this  constituent  that  man  so  universally  and 
commonly  uses  butter  in  his  daily  diet.  Butter  fat  is  un- 
doubtedly the  most  readily  digested  and  easily  assimilated 
of  this  class  of  foods.  It  is  also  more  agreeable  in  flavor 
than  any  other  fat.  In  chemical  composition  butter  fat  is 
similar  to  the  other  common  vegetable  and  animal  fats  and 
oils ;  that  is,  it  is  composed  of  glycerin  and  a  number  of 
fatty  acids  of  which  oleic  and  palmitic  constitute  about  71 
per  cent.  About  20  per  cent  is  composed  of  volatile  fatty 
acids.  The  peculiar  characteristics  of  butter  are  undoubt- 
edly due  to  the  presence  of  these  acids.  One  of  these  acids 
has  taken  its  name  from  butter,  being  called  butyric  acid. 
The  average  composition  of  butter  fat  is  given  in  the  fol- 
lowing table : 

TABLE  XIX 
Composition  of  Butter  Fat 

Acids                                  Percent  Acids                                    Percent 

Dioxystearic 1                   Laurie 2.57 

Oleic 32.50              Capric 0.32 

Stearic 1.83              CajJrylic 0.49 

Palmitic 38.61              Caproic 2.09 

Myristic 9.89              Butyric 5.45 

Glycerin 5.25  per  cent 

Constituents  of  butter.  The  various  constituents  of  but- 
ter may  easily  be  separated  in  the  following  manner: 
A  piece  of  butter  is  placed  in  a  test  tube  or  other  glass 
vessel.  It  is  melted  by  placing  the  vessel  in  warm  water 
or  by  applying  other  gentle  heat  and  then  allowed  to  stand 
for  a  few  moments.    The  butter  fat  forms  the  clear  upper 


BUTTEE  AND  ITS  SUBSTITUTES  73 

yellow  layer.  Underneath  the  fat  the  casein  collects  as 
a  white  solid,  while  at  the  bottom  is  formed  a  colorless, 
watery  portion  which  is  a  solution  of  the  salt  and  the 
small  amount  of  sugar  present  in  the  butter. 

The  flavor  of  butter.  Considerable  care  is  necessary  to 
produce  butter  having  a  perfectly  sweet  and  agreeable 
flavor.  While  this  does  not  add  directly  to  the  nourishing 
constituents  of  an  article  of  food,  it  is  of  great  value  in 
inciting  the  flow  of  the  digestive  fluids  and  promoting  good 
digestion,  especially  in  the  case  of  persons  of  acute  sensa- 
tions. Delicacy  of  flavor  also  adds  very  materially  to  the 
price  which  may  be  obtained  for  an  article  of  food.  The 
development  of  flavor  in  butter  seems  to  be  due  entirely 
to  bacterial  action.  By  introducing  pure  cultures  of  the 
right  kind  of  bacteria  into  sweet  cream,  butter  of  most  ex- 
cellent flavor  will  be  obtained.  Other  bacteria  develop 
very  disagreeable  odors  and  tastes.  By  controlling  the  bac- 
terial content  of  the  cream,  the  best  modern  dairies  pro- 
duce butter  of  very  uniform  and  excellent  flavor.  Much 
butter,  however,  is  still  produced  by  small  dairies  accord- 
ing to  old-fashioned  methods  by  which  any  bacteria  by 
chance  present  are  allowed  to  act  on  the  cream  before  it  is 
churned.  Carelessness  in  handling  both  cream  and  butter 
leads  in  many  cases  to  the  production  of  butter  which  is 
far  too  rancid  and  disagreeable  in  flavor  to  be  sold  for 
table  use.  Much  of  this  butter  is  subjected  to  a  process 
of  purification. 

Renovated  or  process  butter,  as  such  a  purified  product 
is  called,  has  been  treated  as  follows:  The  poorly  made 
butter  is  first  melted  in  large  tanks.  By  blowing  air  through 
the  melted  fat  most  of  the  disagreeable  odor  is  removed. 
The  casein  and  brine  which  are  allowed  to  settle  to  the 
bottom  of  the  tank  contain  most  of  the  bacteria  producing 


74  PUEE  FOODS 

the  decomposition  and  disagreeable  taste.  The  clear  fat, 
which  is  now  quite  sweet,  is  drawn  off  and  mixed  with 
sweet  milk  and  the  whole  churned.  The  remainder  of  the 
process  is  identical  with  that  of  making  butter  from  cream. 
The  resulting  product  has  generally  a  fairly  sweet  odor  and 
taste  and  finds  a  ready  market.  It  differs  somewhat  in  com- 
position from  that  of  true  butter.  While  it  is  a  wholesome 
and  nutritious  article  of  diet,  it  is  inferior  in  flavor  to  good 
butter  and  is  sold  at  a  much  lower  price.  In  most  states 
its  sale  is  carefully  regulated  by  law,  with  the  intent  that 
the  purchaser  shall  clearly  understand  that  he  is  not  buying 
creamery  butter.  For  this  purpose  the  words  "  renovated 
butter  "  must  be  printed  on  the  package  and  also  displayed 
on  a  conspicuous  sign  over  the  article  on  sale. 

Oleomargarine  or  butterine.  This  is  the  name  given  to 
butter  substitutes  in  which  a  portion  or  all  of  the  butter 
fat  has  been  replaced  by  a  foreign  fat.  As  has  been  already 
stated,  all  fats  are  very  similar  in  composition,  and  only  a 
small  portion  of  the  constituents  of  butter  fat  differs  from 
other  ordmary  fats  and  oils.  The  attempt  has  therefore 
been  made  to  find  a  combination  of  various  animal  and 
vegetable  fats  which  is  similar  in  composition  and- proper- 
ties to  natural  butter  fat.  The  manufacturer  is  restricted 
to  fats  and  oils  which  are  cheaper  than  butter  fat  and  can 
be  readily  obtained.  For  this  and  other  reasons  the  attempt 
to  make  artificial  butter  has  been  only  partially  successful. 
A  perfectly  wholesome  and  nutritious  product  has  been 
obtained  without,  however,  having  the  flavor  of  butter 
nor  its  peculiar  adaptability  to  the  digestive  system,  so 
that  it  can  be  continually  eaten  with  relish.  For  this  rea- 
son some  natural  butter  is  almost  invariably  mixed  with 
the  artificial  product  in  order  to  give  it  an  agreeable  taste 
and  odor. 


BUTTER  AND  ITS  SUBSTITUTES 


75 


Wholesomeness  of  oleomargarine.  The  manufacture  of 
oleomargarine  is  carried  on  under  strict  government  con- 
trol and  inspection  so  that  no  unsanitary  methods  nor  un- 
wholesome ingredients  are  allowed  to  be  used.  As  the 
ingredients  used  are  wholesome  and  nutritious  articles  of 
food,  oleomargarine  cannot  be  condemned  as  a  food...  The 
opposition  to  it  has  arisen  from  the  fact  that  it  has  often 


Fig.  10.    Wrapping  and  Packing  Butterine  for  Shipment 

been  offered  and  sold  as  butter.  This  practice  not  only 
defrauds  the  customer  but  tends  to  drive  the  genuine  arti- 
cle out  of  the  market,  as  it  cannot  be  produced  at  as  low 
a  cost  as  oleomargarine.  When  sold  for  what  it  is  and  at 
a  lower  price  than  butter,  oleomargarine  undoubtedly  ren- 
ders the  fat  element  of  human  diet  available  to  people  who 
could  not  afford  the  more  expensive  butter.  While  a  good 
grade  of  oleomargarine  is  a  more  wholesome  and  palatable 


76  PUKE  FOODS 

article  of  food  than  a  poor  grade  of  butter,  the  best  grades 
of  butter  have  a  finer  flavor  and  are  more  easily  assimilated 
than  any  substitute  as  yet  produced.  The  keeping  qualities 
of  good  oleomargarine  are  excellent.  Mixtures  of  oleomar- 
garine and  butter  in  various  proportions  are  very  palatable 
and  considerably  cheaper  than  pure  butter. 

The  practice  of  coloring  butter  with  vegetable  or  aniline 
dyes  is  very  general,  but  if  the  dye  is  not  a  poisonous  one, 
there  can  be  little  objection  to  the  practice. 

Manufacture  of  oleomargarine.  Both  animal  and  vege- 
table fats  and  oils  are  used  in  the  manufacture  of  oleomar- 
garine. The  finest  neutral  lard  is  heated  to  45°  C.  for 
some  time  and  then  subjected  to  hydraulic  pressure.  Most 
of  the  stearin  is  removed  in  this  manner  and  used  for  other 
purposes,  while  the  oleo  oil  forms  the  raw  material  for  the 
manufacture  of  the  artificial  butter.  The  most  commonly 
used  vegetable  oil  is  cottonseed,  which  together  with  oleo 
oil  and  milk  are  placed  in  churning  machines  which  serve 
to  beat  the  oils  into  minute  drops  resembling  the  con- 
dition of  the  fat  in  natural  butter.  In  some  cases  coloring 
matter  is  added  as  well  as  substances  which  give  taste  and 
odor  similar  to  butter.  Generally  a  small  amount  of  but- 
ter is  also  introduced  for  the  same  purpose. 

EXPERIMENTS 

18.  The  foam  test  for  butter.  Place  a  tablespoonf  ul  of  pure  butter, 
renovated  or  process  butter,  and  oleomargarine  in  each  of  three  small 
beakers  or  other  suitable  vessels.  Heat  over  the  Bunsen  burner  or  a 
stove  until  the  samples  melt.  On  continued  heating,  the  butter  boils 
quietly,  producing  considerable  foam,  while  the  oleomargarine  and 
the  renovated  butter  produce  very  little  foam  and  sputter  and  crackle 
violently. 

19.  The  milk  test.  Place  a  tablespoonf  ul  of  each  of  the  three  sam- 
ples used  in  Experiment  18  in  each  of  three  small  beakers  or  small 


BUTTER  AND  ITS  SUBSTITUTES  77 

cups  containing  a  few  ounces  of  sweet  milk  and  warm  gently  until 
the  samples  are  melted.  Place  the  vessels  in  cold  water,  and  while 
the  fat  is  still  melted,  stir  vigorously  with  wooden  sticks  of  con- 
venient size.  As  the  fat  hardens,  it  will  be  found  that  the  pure  and 
renovated  butter  will  make  an  emulsion  with  the  milk  very  similar 
to  cream,  while  the  oleomargarine  will  not  mix  with  the  milk  but 
will  solidify  into  a  solid  chunk  of  fat,  which  will  often  adhere  to 
the  stick  so  that  it  can  be  lifted  out  of  the  milk. 

As  cottonseed  oil  is  frequently  used  in  the  manufacture  of  oleo- 
margarine, the  test  for  this  oil  by  means  of  Halphen's  reagent,  as 
given  on  page  70,  is  of  great  assistance  in  proving  the  presence  of 
oleomargarine. 


CHAPTER  VIII 

MEATS 

The  importance  of  meat  in  the  diet.  Meats  are  of  impor- 
tance in  the  human  diet  on  account  of  their  high  content  of 
protein.  The  solid  portion  of  the  lean  of  meat  is  very  nearly 
pure  protein,  containing  only  very  small  amounts  of  fat, 


Fig.  Jl.   A  Train  of  Cattle  Cars  bringing  Stock  from  the  Western 
Plains  to  Chicago 

carbohydrates,  and  mineral  matter.  The  average  composi- 
tion of  lean  meat  may  be  given  as  25  per  cent  protein  and 
75  per  cent  water.  The  presence  of  protein  in  the  human 
diet  is  of  the  highest  importance,  because  the  protoplasm 
or  living  portion  of  the  human  system  can  be  built  up  and 
nourished  only  by  this  constituent  of  our  food.  If  it  were 
entirely  absent,  we  should  starve  to  death  as  certainly  as  if 
we  ate  no  food  at  all,  although  by  no  means  as  quickly. 

Substitutes  for  meat.    We  are  by  no  means  compelled  to 
eat  meat  in  order  to  obtain  this  valuable  constituent  of  our 

78 


MEATS 


79 


food,  because  many  vegetable  foods  contain  protein  in  large 
amounts.  It  seems,  however,  that  the  protein  of  meat  is 
much  more  easily  digested  and  more  readily  assimilated  by 
the  tissues  than  vegetable  protein,  so  that  meats  are  a  very 
desirable  constituent  of  the  human  diet.  Most  meats  as 
ordinarily  consumed  contain  considerable  quantities  of  fat, 
so  that  when   eaten  with  potatoes,  which  are  composed 


Fig.  12.   A  Portion  of  the  Chicago  Stockyards 


almost  entirely  of  starch,  the  combination  furnishes  all 
constituents  of  a  complete  diet.  As  meats  are  a  relatively 
expensive  food,  economy  as  well  as  good  health  is  attained 
by  limiting  their  consumption  to  the  amount  actually  neces- 
sary to  meet  the  needs  of  the  system. 

The  danger  of  excessive  use  of  meat.  On  the  other  hand, 
serious  dangers  attend  the  consumption  of  meats,  especially 
in  excessive  quantities.    This  is  due  to  the  fact  that  the 


80  PUKE  FOODS 

decomposition  products  of  protein  are  not  readily  eliminated 
from  the  system,  and  give  rise  to  various  disorders  and 
diseases.  The  proteins  of  meat  also  seem  more  liable  to 
decompose  in  such  a  manner  as  to  give  rise  to  highly  poison- 
ous substances.  The  consumption  of  meat  should  therefore 
be  limited  to  the  amount  necessary  to  build  up  and  repair 
the  tissues  of  the  body.  As  both  growth  and  the  breaking 
down  of  the  tissues  are  very  slow  processes,  the  amount  of 
protein  consumed  need  not  be  large.  It  must  not  be  for- 
gotten that  all  vegetable  foods  contain  some  protein,  and 
some  of  these  foods  contain  a  very  large  percentage  of  this 
constituent.  One  half  pound  of  lean  meat  per  day  taken 
with  other  ordinary  foods  is  therefore  amply  sufficient  for 
the  average  adult. 

Unsanitary  meat.  Meats  may  be  unwholesome  for  a 
number  of  reasons.  The  animal  from  which  the  meat  is 
derived  may  be  diseased  at  the  time  of  slaughter.  Such 
diseases  are  not  necessarily  communicated  to  the  person 
eating  the  meat,  although  in  some  cases  they  may  be.  This 
is  true  of  trichina  in  pork  and  tuberculosis  in  cattle.  The 
animal  also  may  not  be  of  the  proper  age  for  slaughter. 
The  slaughter  of  very  young  calves  is  generally  prohibited 
by  law,  their  flesh  not  being  fit  to  eat.  The  meat  should 
not  be  eaten  if  the  animal  has  died  a  natural  death.  The 
meat  from  perfectly  healthy  and  sound  animals  may  be 
rendered  unfit  for  food  by  unsanitary  methods  of  slaughter 
and  handling  of  the  meat. 

Inspected  meat.  As  it  is  almost  impossible  in  many  cases 
by  an  examination  of  meat  or  meat  products  to  obtain 
evidence  that  the  animals  were  unfit  for  food  or  that  the 
meat  was  improperly  handled,  an  essential  part  of  any 
effective  method  of  protecting  the  public  against  an  un- 
wholesome supply  is  a  rigid  inspection  of  the  animals  before 


MEATS  81 

slaughter,  as  well  as  the  method  of  handling  the  meat  until 
it  reaches  the  consumer.  Such  a  system  of  inspection  is 
now  maintained  by  the  national  government. 

Characteristics  of  sound  meat.  The  purchaser  may,  how- 
ever, in  many  cases  distinguish  between  wholesome  and 
unwholesome  meat  by  an  inspection  of  the  article  as  offered 
for  sale.  Sound  fresh  meat  should  have  the  following 
characteristics :  The  color  should  be  neither  pale  pink  nor 
dark  purple.  In  the  first  case  the  animal  was  probably 
diseased;  in  the  second  case  it  was  not  slaughtered  but 
died  a  natural  death.  Fresh  meat  should  be  firm  and  elastic 
to  the  touch  and  should  hardly  moisten  the  finger.  Wet, 
sodden,  or  flabby  meat,  which  is  soft  and  jellylike  to  the 
touch,  should  not  be  used.  Moreover  fresh  meat  should 
be  almost  free  from  odor.  Diseased  meat  has  a  sickly  dis- 
agreeable odor.  On  standing  a  day  or  two  it  should  grow 
drier,  but  should  not  become  wet.  The  following  simple 
chemical  tests  may  also  be  applied  in  doubtful  cases:  It 
should  be  acid  toward  litmus  or  other  indicator ;  that  is,  it 
should  turn  blue  litmus  paper  red.  If  it  is  neutral  or  alka- 
line, preservatives  such  as  borax  have  been  used.  When 
dried  at  100°  C.  it  should  not  lose  more  than  70  to  74  per 
cent  in  weight.  Unsound  meat  may  lose  80  per  cent  or 
more.    On  cooking,  it  should  shrink  very  little. 

Similarity  of  various  kinds  of  meat.  Although  the  various 
kinds  of  meat,  such  as  pork,  beef,  mutton,  etc.,  differ  con- 
siderably in  taste  and  ease  of  digestion,  chemically  they  are 
so  similar  that  it  is  quite  difficult  to  identify  the  ingredients 
of  a  mixture  of  these  meats  if  they  have  been  chopped  fine 
so  that  no  large  pieces  remain. 

Refrigeration  of  meat.  The  only  method  of  preserving 
fresh  meat,  which  is  generally  conceded  to  be  unobjection- 
able, is  by  refrigeration.  There  is  some  difference  of  opinion 


82 


PURE  FOODS 


as  to  how  long  meat  may  be  kept  in  this  manner  without 
deterioration.  Some  observers  report  that  the  meat  begins 
to  deteriorate  after  three  months,  while  other  investigators 
find  no  change  after  as  many  years.  It  seems,  however,  that 
the  condition  of  the  meat  is  affected  by  the  temperature  to 
which  it  is  exposed  and  also  by  the  conditions  under  which 
it  is  allowed  to  thaw.    To  obtain  the  best  results,  the  meat 


Fig.  13.    Meat  in  Cold  Storage 

must  be  subjected  to  a  temperature  low  enough  to  freeze 
it  solid;  that  is,  none  of  its  juices  should  remain  liquid. 
This  result  is  obtained  with  beef  by  keeping  it  at  a  tem- 
perature at  or  below  —  9°  C.  or  16°  F.  When  such  meat  is 
thawed,  it  should  be  allowed  to  warm  up  very  slowly,  as 
otherwise  it  will  be  flabby.  This  is  due  to  the  fact  that 
during  the  process  of  freezing  the  juices  have  been  forced 
out  of  the  cells.  If  warmed  up  slowly,  these  juices  reenter 
the  cells  slowly,,  so  that  the  meat  assumes  its  natural  firm 
condition. 


MEATS 


83 


Chemical  preservatives.  These  substances  have  been  used 
quite  extensively  in  preserving  meats.  Boric,  sulphurous, 
and  benzoic  acids  have  been  most  generally  employed.  In 
addition  to  preserving  the  meat,  sulphurous  acid  has  also 
the  property  of  giving  it  a  bright  red  color.  Saltpeter  or 
potassium  nitrate  has  the  same  effect  on  the  color  of  the 
meat,  but  this  salt  has  very  little  preserving  power.    Meat 


Fig.  14.   Packing  Poultry  for  Shipment 

which  contains  a  chemical  preservative  will  emit  no  dis- 
agreeable odor,  even  when  it  is  so  old  and  decomposed  that 
without  the  preservative  it  would  be  quite  foul.  If  sulphur- 
ous acid  is  used,  the  meat  will  also  retain  the  bright  red 
color  of  fresh  meat.  The  use  of  these  substances,  there- 
fore, renders  possible  the  sale  of  meat  which  would  other- 
wise be  discarded.  Such  meat  is  sometimes  used  for  the 
preparation  of  sausage.  The  sulphurous  acid  is  introduced 
as  sodium  or  calcium  sulphite.    The  red  color  is  sometimes 


84 


PURE  FOODS 


restored  to  decomposed  meat  by  the  addition  of  coal-tar 
dyes,  cochineal,  or  red  ocher. 

Objections  to  the  use  of  preservatives.  The  treatment  of 
meat  with  coloring  matter  or  preservatives  is  to  be  con- 
denmed,  and  the  sale  of  such  meat  is  illegal.  While  it  is 
possible  to  find  preservatives  and  coloring  matter  that  are 
not  demonstrably  unwholesome  in  the  minute  amounts  that 


Fio.  15.    A  llooniful  uf  Lard 

it  is  necessary  to  employ,  it  is  obvious  that  if  the  meat  were 
in  good  condition,  neither  preservatives  nor  coloring  matter 
would  be  necessary.  As  these  substances  are  added  for  the 
purposes  of  deceiving  the  customer,  their  use  is  fraudulent. 
The  use  of  saltpeter  or  potassium  nitrate  in  corned  beef  is 
not  considered  fraudulent,  because  the  meat  so  treated  is 
not  injured,  and  the  custom  has  been  long  established. 

Gelatin.   This  is  one  of  the  most  commonly  used  of  meat 
products.     It  is  a  nitrogenous  substance,   which  has  the 


MEATS  85 

property  of  forming  a  jelly  with  a  very  large  amount  of 
water.  Good  gelatin  will  form  a  jelly  with  fifty  times  its 
weight  of  water.  It  is  extracted  from  the  bones,  tendons, 
and  hides  of  the  slaughtered  animals.  Tendons  and  hides 
are  first  treated  with  lime  to  remove  hair  and  dissolved 
mucin.  After  washing,  the  gelatin  is  dissolved  out  by 
means  of  hot  water.  Sulphurous  acid  is  sometimes  added 
in  order  to  produce  a  white  product.  After  drying  and 
powdering,  the  gelatin  is  ready  for  use.  It  is  not  pres- 
ent as  such  in  the  bones,  hides,  etc.  A  substance  called 
collagen,  very  similar  to  gelatin,  is  present  and  is  con- 
verted by  the  hot  water  into  gelatin.  Gelatin  is  a  per- 
fectly wholesome  article  of  food  if  carefully  made  from 
fresh  material.  It  decomposes  very  readily  and  may  be  con- 
taminated with  tetanus  and  other  disease  bacteria  unless 
the  greatest  cleanliness  is  observed  during  its  manufacture. 

EXPERIMENTS 

20.  Testing  meat  for  borax.  Test  samples  of  meat  for  borax  or  bo- 
ric acid  according  to  the  method  given  in  Experiment  10,  p.  40. 
Prepare  samples  of  meat  containing  borax  by  sprinkling  the  powder 
over  the  surface  of  the  meat.  Use  a  portion  of  the  sample  for  mak- 
ing the  test  for  borax,  and  set  aside  the  other  portion  for  observation 
on  the  preservative  action  of  the  borax,  a  sample  of  the  untreated 
meat  being  placed  with  the  preserved  sample. 

21.  Testing  meats  for  sulphites.  Sulphites  are  largely  used  to  pre- 
serve and  give  a  bright  red  color  to  chopped  meats  or  "Hamburg 
steak."  Samples  of  such  meat  may  be  tested  as  follows :  A  small 
portion  is  placed  in  a  small  dish  or  beaker  and  moistened  with 
dilute  phosphoric  acid  and  then  heated  gently.  If  a  large  amount  of 
sulphite  has  been  added,  the  sulphur  dioxide  evolved  on  heating  can 
be  detected  by  the  odor,  which  is  that  of  burning  sulphur. 

A  much  more  delicate  test  consists  in  exposing  a  piece  of  starch- 
iodate  paper  to  the  action  of  the  gases  and  steam  arising  when 
heating  the  meat  with  phosphoric  acid.  If  sulphites  are  present,  the 
paper  is  turned  blue.    The  starch-iodate  paper  is  prepared  by  first 


86 


PUEE  FOODS 


making  thin  starch  paste.  The  starch  is  made  into  a  thin  paste  with 
cold  water,  which  is  diluted  by  adding  a  considerable  amount  of  boil- 
ing water  while  stirring  continually.  A  few  crystals  of  potassium 
iodate  are  dissolved  in  water  and  added  to  the  starch  paste.  Strips 
of  filter  or  other  porous  paper  are  then  dii:)ped  into  the  solution  and 
drained  and  allowed  to  dry.  This  paper  should  be  preserved  in  well- 
stoppered  bottles. 

A  still  more  delicate  test  for  sulphites  is  carried  out  as  follows : 
40-50  gm.  of  the  meat  to  be  tested  is  mixed  with  water  and  heated 


Fig.  16.    Distillation  of  Sulphurous  Acid 

for  a  few  minutes.  Ten  ccm.  of  glacial  phosphoric  acid  is  added  and 
the  solid  material  strained  off  through  a  cotton  cloth.  The  solution 
is  then  placed  in  the  second  flask,  shown  in  Fig.  16,  and  distilled. 
The  water  in  the  first  flask  is  brought  to  a  boil.  The  steam  entering 
the  second  flask  heats  the  solution  of  the  meat.  The  Bunsen  burner 
under  the  second  flask  is  then  lighted  and  the  flame  of  the  Bunsen 
burners  regulated  so  that  the  meat  solution  is  kept  gently  agitated 
without  any  great  change  in  volume.  The  distillate  is  received  in  a 
beaker  containing  a  little  bromine  water.  After  about  200  ccm.  has 
been  distilled  over,  the  bromine  is  boiled  out,  a  little  hydrochloric 


MEATS  87 

acid  is  added,  and  then  a  few  drops  of  a  10  per  cent  barium  chloride 
solution  are  added  to  the  boiling  hot  solution.  After  boiling  for  some 
time,  the  solution  is  set  aside  to  cool  and  examined  carefully  for  the 
presence  of  a  precipitate.  A  white  precipitate  is  evidence  that  a 
sulphite  has  been  added  to  the  meat.  A  very  slight  precipitate  is 
generally  obtained,  even  from  pure  meat,  because  the  protein  of  meat 
contains  a  small  amount  of  sulphur,  part  of  which  is  carried  over 
during  the  distillation  process. 

Tests  should  be  carried  out  on  samples  of  pure  meat  before  and 
after  the  addition  of  weighed  amounts  of  sulphites.  Sodium  or  cal- 
cium sulphites  may  be  used  for  this  purpose. 

The  amount  of  sulphite  which  has  been  added  to  the  meat  may 
be  accurately  determined  by  weighing  the  barium  sulphate  obtained 
in  the  distillate  from  a  weighed  amount  of  meat.  For  this  purpose 
the  precipitate  is  filtered  off  on  an  ashless  filter  paper  and  washed 
thoroughly  with  hot  water.  The  wet  paper  with  the  precipitate  is 
placed  in  a  weighed  crucible  and  the  paper  burned  by  gently  heating 
the  crucible,  which  is  finally  strongly  heated,  cooled,  and  weighed. 
One  gram  of  barium  sulphate  is  equivalent  to  0.2745  gm.  of  sulphur 
dioxide.^ 

1  For  detailed  instructions  for  this  determination  see  the  author's  text- 
book, "Quantitative  Chemical  Analysis." 


.      CHAPTER  IX 
carbohydrates 

Starch,  Sugar,  and  Sirups 

Importance  of  carbohydrates  in  the  diet.  While  gen- 
erally occurring  in  natural  products  together  with  other 
constituents,  this  important  class  of  foods  may  be  sep- 
arated in  a  very  nearly  pure  condition,  just  as  fats  and 
protein  are  available  without  admixture  with  other  food 
constituents.  As  the  human  system  seems  to  be  able  to 
obtain  the  necessary  supply  of  energy  most  economically 
from  carbohydrates,  their  preparation  as  food  is  very  im- 
portant. This  consists  essentially  of  two  processes:  first, 
their  separation  from  other  substances  with  which  they 
are  associated  in  natural  products ;  and  second,  the  con- 
verting of  insoluble  into  soluble  compounds.  Starch  is  the 
most  common  insoluble  form,  while  the  sugars  and  sirups, 
honey,  etc.  are  common  illustrations  of  soluble  carbohy- 
drates. Starch  is  a  very  large  constituent  of  nearly  all 
seeds  and  grains,  such  as  wheat,  corn,  rice,  etc.,  while  the 
sugars  are  present  in  large  quantities  in  nearly  all  fruits 
and  in  the  juices  of  many  plants,  such  as  sugar  cane,  the 
maple  tree,  etc. 

Necessity  of  cooking  starch.  The  digestion  of  starch  con- 
sists essentially  in  its  conversion  into  simple  soluble  forms. 
In  the  preparation  of  food  products  the  starch  may  be 
subjected  to  a  similar  process  so  as  to  render  it  more  or 
less  soluble.  It  is  then  more  easily  digested.  It  is  very 
essential  to  start  this  conversion  before  starch  is  eaten,  as 


CAEBOHYDRATES  89 

raw  starch  is  quite  indigestible.  The  process  of  cooking  by 
roasting  or  boiling  renders  the  starch  sufficiently  soluble  for 
rapid  action  by  the  digestive  fluids.  On  the  other  hand,  it  is 
not  advisable  to  consume  only  starch  which  has  been  fully 
converted  into  soluble  forms  (mainly  the  sugars),  because 
such  food  is  almost  immediately  taken  into  the  circulation. 


Fig.  17.    Steel  Tanks  for  the  Storage  of  Corn 

Each  tank  will  hold  85,000  bushels,  or  85  carloads  of  corn,  which  is  converted 
into  starch,  glucose,  etc.  in  three  days 

At  least  some  food  is  needed  which  will  dissolve  gradually 
and  nourish  the  system  continuously.  A  diet  containing 
both  soluble  and  insoluble  carbohydrates,  such  as  sugar  and 
starch,  is  best  suited  to  meet  the  needs  of  the  system. 

Natural  products  containing  starch.  While  a  very  large 
portion  of  the  starch  consumed  as  food  is  taken  in  its  natural 
condition  in  such  foods  as  potatoes,  rice,  bread,  and  the 
numerous  foods  prepared  from  corn,  oats,  etc.,  it  is  found 


90  PURE  FOODS 

convenient  for  many  purposes  to  separate  the  starch  in  the 
pure  state.  Corn  and  potatoes  are  the  natural  products 
which  have  been  most  largely  used  for  the  manufacture  of 
starch.  Both  of  these  foods  are  composed  almost  entirely 
of  starch,  the  process  of  manufacture  consisting  simply  in 
the  elimination  of  the  other  constituents.  As  corn  can  be 
produced  in  abundance  and  cheaply  in  the  United  States, 
it  is  the  source  from  which  most  of  the  American  starch  is 
made,  while  for  analogous  reasons  the  potato  has  been  used 
in  Europe. 

Structure  of  a  grain  of  corn.  An  examination  of  a  grain 
of  corn  will  show  that  it  has  an  outer  hard  hull  or  shell 
which  protects  the  grain  from  injury.  If  a  grain  be  split 
parallel  to  the  flattened  sides,  the  soft  germ  can  be  seen 
imbedded  in  a  mass  of  starch.  When  the  germ  sprouts 
through  the  action  of  moisture  and  warmth,  the  starch  is 
converted  into  sugars,  which  dissolve  and  are  absorbed  and 
nourish  the  growing  plant.  The  germ  contains  a  consider- 
able amount  of  protein  and  oil,  while  some  protein,  known 
as  gluten,!  jg  also  mixed  with  the  surrounding  layers  of 
starch.  Processes  have  been  developed  for  separating  the 
starch,  protein,  and  oil  very  completely. 

Separation  of  the  germs.  For  this  purpose  the  grain  is 
first  steeped  in  water  containing  sulphurous  acid.  This 
softens  the  entire  grain,  loosens  the  hull  from  the  re- 
mainder of  the  grain,  and  dissolves  the  gluten  which  serves 
to  bind  the  starch  grains  together.  The  soft  corn  is  then 
passed  through  the  so-called  "  foose  mills,"  which  break  the 
grains  of  corn  into  coarse  particles.  It  is  then  mixed  with 
water  and  pumped  into  the  ''  germ  separators,"  which  are 

iThis  gluten  is  not  identical  with  the  gluten  of  wheat.  It  is  composed  of 
two  proteins,  edestin  and  zein,  while  the  gluten  of  wheat  is  composed  of 
glutenin  and  gliadin. 


CARBOHYDRATES  91 

long,  deep,  steel  tanks.  The  ground  corn  suspended  in  the 
water  is  delivered  into  the  upper  end  of  these  tanks.  The 
germs  being  light,  on  account  of  their  content  of  oil,  float  on 
top  and  are  swept  to  the  lower  end  by  means  of  strips  of 
wood,  which  are  moved  slowly  over  the  surface  of  the  liquid 
by  means  of  belts  to  which  they  are  attached.  The  starch 
and  hulls  being  heavy  drop  to  the  bottom  and  are  carried 
away  in  separate  conveyors.  In  this  very  simple  manner 
the  germs  which  have  been  left  practically  intact  are  sepa- 
rated very  completely  from  the  starch  and  hulls. 

Production  of  corn  oil.  By  subjecting  the  germs  to  pres- 
sure corn  oil  may  be  produced,  which  is  used  for  making 
soap,  or,  when  refined,  as  a  cooking  oil ;  or  it  may  be  con- 
verted into  a  substitute  for  rubber.  The  germs  remaining 
in  the  strong  canvas  bags  of  the  oil  press  form  what  is 
known  as  "oil  cake."  This  still  contains  a  smair amount 
of  oil  as  well  as  a  large  amount  of  protein  and  starch  and 
some  mineral  matter.  It  has  been  found  to  be  an  excellent 
cattle  food  and  is  largely  used  by  dairymen  to  increase  the 
yield  of  milk  and  butter. 

Manufacture  of  starch.  The  starch  and  hulls  which  set- 
tle to  the  bottom  of  the  "germ  separators"  are  next  passed 
over  the  so-called  "  shakers."  These  consist  of  frames  cov- 
ered with  perforated  copper,  copper  gauze,  or  silk  bolting 
cloth.  By  means  of  machinery  they  are  kept  in  constant 
motion,  back  and  forth,  which  gives  the  name  "  shaker " 
to  the  apparatus.  The  finer  particles  of  the  starch  pass 
through  the  shaker,  while  the  coarse  particles,  consisting 
of  hulls  with  some  attached  starch,  are  carried  over  the 
end  of  the  shaker.  This  material  is  again  ground  in  bur 
or  stone  mills,  and  again  passed  over  shakers  in  order 
to  remove  the  remainder  of  the  starch  from  the  hulls. 
The  starch  which  has  passed  through  the  shakers  is  held 


92  PURE  FOODS 

suspended  in  water,  forming  the  so-called  "  starch  liquor," 
which  is  pumped  to  the  starch  tables.  These  are  long 
wooden  troughs  slightly  inclined.  The  starch  liquor  enters 
the  trough  at  the  upper  end,  and  as  it  flows  slowly  to  the 
lower  end  the  starch  settles  to  the  bottom,  forming  a  com- 
pact layer,  while  the  gluten  and  the  water  flow  out  at  the 
lower  end.  The  starch  is  then  shoveled  into  conveyors, 
which  carry  a  portion  of  it  to  the  drying  rooms  to  be 
made  up  into  the  various  forms  of  dried  starch.  A  single 
factory  produces  annually  75,000,000  pounds  of  starch  in 
this  manner  from  corn. 

The  conversion  of  starch  into  sirup  and  sugar.  While  a 
considerable  quantity  of  starch  is  used  in  foods,  laundry 
work,  and  many  technical  processes,  a  very  considerable 
proportion  is  converted  into  glucose  or  corn  sirup  and 
starch  sugar.  These  substances  are  chemically  very  similar 
to  starch,  differing  mainly  in  that  they  are  soluble  and 
sweet,  while  starch  is  very  insoluble  and  almost  tasteless. 
They  are  also  much  more  easily  digested.  When  starch  is 
to  be  converted  into  glucose,  or  starch  sugar,  it  is  sus- 
pended in  water  and  a  small  amount  of  hydrochloric  acid 
is  added.  The  starch  liquor  is  pumped  into  closed  copper 
tanks,  called  "  converters,"  in  which  it  is  heated  by  means 
of  steam  under  pressure.  Under  these  conditions  the  starch 
undergoes  a  transformation  by  which  it  takes  up  a  small 
amount  of  water  and  forms  soluble  compounds  similar  to 
sugar,  so  that  the  liquor  acquires  a  sweet  taste.  Because 
the  starch  combines  with  water,  this  process  is  called  hydrol- 
ysis. The  compounds  produced  are  mainly  dextrine  and 
dextrose.  The  first  substance  formed  is  dextrine,  which  may 
be  called  a  soluble  gum  and  is  largely  used  for  mucilage  and 
other  pastes.  The  same  substance  is  formed  in  the  crust  of 
bread  during  the  process  of  baking.    On  further  heating 


CARBOHYDKATES 


93 


with  acid,  the  dextrine  breaks  down  still  further  into  two 
sugars,  maltose  and  dextrose.  On  continued  heating  the 
maltose  is  also  broken  down  into  dextrose,  leaving  this 
product  only.   The  sugars  are  not  the  same  as  ordinary 


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Fig.  18.   Top  of  Charcoal  Filters 
The  sirup  flows  into  the  filter  through  the  curved  pipes 

granulated  or  cane  sugar,  which  is  known  as  sucrose.  Dex- 
trose is  less  sweet  than  sucrose,  so  that  glucose  is  only 
about  three  fifths  as  sweet  as  ordinary  sugar.  If  the  heat- 
ing of  the  starch  liquor  is  prolonged,  the  starch  is  converted 
almost  completely  into  dextrose,  which  crystallizes  out  and 
forms  what  is  known  as  starch  sugar  or  corn  sugar. 


94  PUKE  FOODS 

Purification  of  the  sirup.    After  the  starch  has  been  con- 
verted into  sugars  in  this  manner  the  hydrochloric  acid  is 


Fig.  19.  Body  of  Charcoal  Filter,  which  is  a  Steel  Tank  entirely  tilled 
with  the  Sirup  and  Charcoal 

neutralized  with  soda  ash  and  converted  into  sodium  chlo- 
ride, which  is  the  main  constituent  of  common  salt.    Some 


CARBOHYDRATES 


95 


of  the  impurities  in  the  Hquid  separate  out  at  this  stage  of 
the  process  and  are  removed  by  filtration  through  canvas 


Fig.  20.   Vacuum  Pan  for  Concentration  of  the  Sirup 
The  capacity  of  the  pan  is  100  barrels  of  sirup 

in  filter  presses.  After  passing  through  these  presses  the 
solution  is  clear  and  transparent,  but  dissolved  impurities 
give  it  a  yellow  color.    To  remove  these  impurities  and 


96  PURE  FOODS 

decolorize  the  solution,  it  is  passed  into  large  steel  tanks 
filled  ^with  bone  char.  The  charcoal  or  carbon  present  in 
this  material  absorbs  the  impurities  and  clarifies  the  solu- 
tion. The  same  material  is  used  in  the  same  manner  for 
clarifying  solutions  of  ordinary  sugar,  or  sucrose.  The 
bone  char  may  be  used  repeatedl}^,  as  the  impurities  are 
burned  out  in  specially  designed  kilns. 

Concentration  of  the  sirup.  In  the  next  and  final  step 
in  the  process  the  solution  is  converted  into  a  thick  sirup 
by  removing  the  excess  of  water.  This  is  done  by  boiling 
the  liquid  in  a  vacuum  until  the  desired  concentration  has 
been  reached.  The  finished  product  is  a  thick,  colorless, 
transparent  liquid  known  as  glucose,  or  corn  sirup.  For- 
merly sulphurous  acid  was  added  to  prevent  its  turning 
yellow.  On  account  of  the  pure-food  agitation  this  prac- 
tice has  been  discontinued  except  when  the  glucose  is  ex- 
ported to  countries  where  the  presence  of  sulphurous  acid 
is  not  prohibited. 

Composition  of  com  sirup.  Glucose,  or  corn  sirup,  there- 
fore, is  a  solution  of  dextrose  and  dextrine  and  similar 
sugars,  in  smaller  amount,  as  formed  by  the  chemical  com- 
bination of  water  and  starch.  These  compounds  are  formed 
whenever  starch  is  heated  to  the  proper  temperature.  How- 
ever, when  moist  starch  is  heated,  dextrine  is  the  main 
product  produced.  This  is  quickly  hydrolyzed  by  the 
saliva,  forming  maltose  and  dextrose,  which  give  the  sweet 
taste.  For  this  reason  a  baked  potato  is  sweeter  than  a 
boiled  potato,  and  the  crust  of  bread  sweeter  than  the  in- 
terior. Many  natural  products,  especially  fruits,  contain 
large  quantities  of  the  same  compounds.  Honey  is  a  nat- 
ural "  sirup,"  which  is  very  similar  in  composition  to  glu- 
cose, or  corn  sirup,  containing  dextrose,  levulose,  and 
sucrose,  but  no  maltose.    The  only  compound  present  in 


CAEBOHYDRATES  97 

glucose  which  is  not  derived  from  the  starch  is  the  salt 
formed  by  the  neutralization  of  the  hydrochloric  acid  with 
soda  ash.  The  word  ''  glucose  "  means  sweet  and  was  adopted 
for  this  reason.  The  name  "  corn  sirup  "  has  been  adopted  in 
this  country  because  it  is  made  from  corn  and  has  the 
physical  properties  of  a  sirup.  In  Europe,  however,  glucose 
is  made  almost  entirely  from  potato  starch  and  sometimes 
from  broken  and  low-grade  rice. 

Table  sirup.  Most  of  the  table  and  cooking  sirups  on 
the  market  to-day  are  composed  very  largely  of  corn  sirup. 
It  cannot  be  used  in  the  pure  state  for  this  purpose  because 
it  is  quite  insipid.  It  is  therefore  blended  with  ''refiners' 
sirup,"  or  molasses  from  the  sugar  refiners,  which  has 
generally  too  strong  a  flavor  to  be  used  alone.  Glucose  is 
also  very  extensively  used  in  the  manufacture  of  candy. 
It  is  also  largely  used  m  the  manufacture  of  jams,  jellies, 
and  other  fruit  preparations,  as  well  as  for  many  other 
minor  purposes. 

Nutritive  value  of  glucose.  Because  glucose  is  rarely 
ever  sold  at  retail  in  the  pure  state  under  its  own  name, 
or  used  as  such  in  the  household,  but  has  invariably  been 
sold  in  combination  with  some  other  food  and  under  some 
other  name,  without  any  statement  or  intimation  of  its 
presence,  it  has  almost  universally  been  considered  an 
adulterant.  This  classification  has  been  correct  because  the 
purchaser  almost  always  was  under  the  impression  that 
sugar  had  been  used  in  the  preparation  of  the  product  ob- 
tained. The  assumption  that  glucose  is  unwholesome  or 
injurious  or  even  of  little  or  no  food  value  is  absolutely 
erroneous.  On  the  contrary,  it  is  a  highly  nutritious  food, 
having  an  energy  value  of  1777  calories  per  pound,  and  is 
very  readily  digested  and  assimilated.  It  is  inferior  to  cane 
sugar  only  in  the  matter  of  flavor.    The  only  valid  objection 


98  PURE  FOODS 

to  its  use  is  removed  when,  in  accordance  with  pure-food 
laws,  its  presence  is  indicated  on  the  label  of  foods  which 
contain  it. 

Amount  of  corn  used  in  producing  corn  products.  Glucose 
will  probably  continue  in  the  future,  as  in  the  past,  to  be  an 
important  part  of  our  food  supply.  This  is  evident  from 
the  fact  that  about  36,000,000  bushels  of  corn  are  used 
annually  for  its  manufacture  in  the  United  States.  This 
amount  of  corn  would  require  about  36,000  cars  to  haul 
it,  and  would  make  a  single  pile  almost  as  high  (500  feet) 
as  Washington  Monument  (555  feet)  in  our  national  capi- 
tal. This  pile  would  be  500  feet  high,  with  a  base  covering 
a  space  equal  to  several  city  blocks ;  that  is,  500  feet  long 
and  500  feet  wide.  There  are  made  annually  1,000,000,000 
pounds  of  corn  sirup,  which  is  sufficient  to  give  to  every 
man,  woman,  and  child  in  the  United  States  12  pounds 
per  annum. 

Manufacture  of  cane  sugar.  The  process  of  manufactur- 
ing ordinary  sugar  is  much  simpler.  It  exists  as  such  in 
the  juices  of  the  sugar  cane  and  sugar  beet.  The  sugar  cane 
is  cut  down  and  passed  through  presses,  which  squeeze  out 
the  juice.  After  the  addition  of  a  little  slaked  lime  to 
remove  impurities  and  to  keep  the  juice  alkaline,  it  is  evapo- 
rated and  the  sugar  crystallizes  out.  This  is  the  raw  or 
brown  sugar.  The  sirup  remaining  after  the  sugar  has  been 
crystallized  out  is  known  as  molasses.  It  contains  the  min- 
eral matter  present  in  the  juices  of  the  cane  as  well  as  any 
impurities  which  may  have  been  introduced  during  the 
process.  Raw  sugar  is  also  obtained  from  beets,  the  sugar 
in  this  case  being  dissolved  out  of  the  tissues  of  the  finely 
divided  beets  by  a  process  of  diffusion. 

Refining  of  cane  sugar.  In  order  to  refine  the  crude  sugar 
it  is  first  moistened  with  sirup  to  dissolve  the  impurities 


CAEBOHYDEATES  99 

and  placed  in  a  centrifuge.  When  this  machine  is  rotated 
at  a  high  speed,  the  sirup  is  thrown  off  the  sugar  crystals. 
These  are  then  dissolved  in  water  and  phosphoric  acid  and 
lime  added.  The  calcium  phosphate  formed  in  this  manner 
carries  down  the  suspended  impurities,  which  are  filtered 
off  by  means  of  canvas  bags.  The  sirup  is  then  filtered 
through  bone  char  and  concentrated  in  vacuum  pans  in 
exactly  the  same  manner  as  the  corn  sirup.  From  the  con- 
centrated sirup  the  sugar  crystallizes  out  and  is  placed  in 
the  centrifuge,  where  it  is  washed  with  water  and  then 
sprinkled  with  water  containing  a  small  amount  of  Prus- 
sian blue  in  order  to  counteract  a  slight  yellowish  tmge. 
After  drying,  the  sugar  is  ready  for  sale. 

EXPERIMENTS 

22.  Starch  test.  Test  for  starch  several  cereals  and  vegetables, 
as  com,  wheat,  potatoes,  etc.  The  starch  test  may  often  be  obtained 
on  vegetables  by  applying  a  drop  or  two  of  iodine  solution  (pre- 
pared as  in  Experiment  1)  to  the  freshly  cut  surface  of  the  vege- 
tables. The  test  may  be  obtained  in  all  cases  by  crushing  a  small 
portion  of  the  vegetable  or  grain  and  treating  with  boiling  hot 
water  for  a  few  minutes.  On  allowing  to  cool'  and  adding  a  few 
drops  of  the  iodine  solution  a  deep  blue  coloration  or  precipitate 
is  produced. 

23.  Conversion  of  starch  into  sugar.  The  conversion  of  starch  into 
sugar  may  be  shown  by  the  following  experiment :  Starch  paste 
is  first  made  by  moistening  a  few  grains  of  starch  with  water  and 
adding  boiling  water  with  constant  stirring.  A  few  cubic  centi- 
meters of  hydrochloric  acid  are  added  and  the  boiling  continued. 
Before  adding  the  acid  a  few  drops  of  the  starch  solution  is  diluted 
with  water  and  iodine  solution  added.  This  test  is  repeated  at  five- 
minute  intervals.  At  each  successive  test  the  blue  color  becomes 
fainter  until  replaced  by  a  brown  color,  indicating  that  the  conver- 
sion of  the  starch  is  completed. 

The  solution  may  now  be  neutralized  with  sodium  carbonate, 
which  is  added  until  the  solution  no  longer  turns  blue  litmus  paper 


100  PUEE  FOODS 

red.  It  is  generally  quite  cloudy  at  this  point  and  should  be  filtered. 
It  may  then  be  concentrated  by  boiling  until  a  sirupy  consistency  is 
reached. 

24.  Action  of  diastase  on  starch.  The  natural  process  of  conver- 
sion of  starch  into  sugar  by  the  enzymes  present  in  the  grains  may 
be  shown  as  follows :  26  gm.  of  malt  are  ground  in  a  mortar 
and  treated  with  1  ccm.  of  cold  distilled  water  for  an  hour  and  then 
filtered.  The  diastase  of  the  malt  is  dissolved  by  the  water.  Equal 
parts  of  this  solution  and  some  thin  starch  paste  are  mixed  and  kept 
at  a  temperature  of  55°  C.  The  conversion  of  the  starch  may  be 
observed  by  means  of  the  iodine  test,  as  directed  in  Experiment  22. 

Various  malt  extracts  (maltine  for  instance)  may  be  purchased 
and  used  in  place  of  the  diastase  extracted  directly  from  the  malt. 
The  rapidity  with  which  equal  portions  of  such  extracts  convert  the 
same  starch  solution  may  be  used  as  a  measure  of  their  strength. 

25.  Digestion  of  starch.  The  conversion  of  starch  into  sugar  by  the 
natural  process  of  digestion  may  be  illustrated  by  the  following 
experiment :  A  few  cubic  centimeters  of  saliva  are  collected  and 
filtered.  A  solution  of  boiled  starch  is  prepared  and  cooled  as  directed 
in  Experiment  22.  The  saliva  is  added,  using  about  10  ccm.  to  100 
ccm.  of  the  starch  solution.  One  half  of  the  mixture  is  made  slightly 
acid  with  hydrochloric  acid.  Both  portions  are  tested  with  the  iodine 
solution  at  regular  intervals.  It  will  be  found  that  no  conversion 
takes  place  in  the  acid  solution.  This  shows  how  the  acid  gastric 
juice  of  the  stomach  stops  the  action  of  the  saliva,  and  emphasizes 
the  necessity  of  chewing  the  food  and  the  evils  of  rapid  eating. 
The  starch  in  the  alkaline  solution  will  be  more  or  less  rapidly  con- 
verted, depending  upon  the  activity  of  the  saliva,  temperature,  and 
amount  of  starch  present. 


CHAPTER   X 

CANDIES 

Cocoa  and  Chocolate 

Function  of  sugar  in  the  diet.  Sugars  and  sirups  are  used 
by  many  people  for  condimental  purposes  only;  that  is, 
they  are  added  to  foods  for  the  purpose  of  giving  a  pleasant 
taste.  As  has  been  shown  in  the  preceding  chapter,  these 
substances  have  a  high  energy  value ;  indeed,  most  of  the 
energy  used  by  the  human  system  is  derived  from  this  class 
of  foods  (the  carbohydrates).  So  that  when  sugar  is  added 
to  tea  or  coffee  or  any  other  food,  its  energy  or  food  value 
is  materially  increased,  the  calorific  value  of  sugar  being 
1860  calories  per  pound.  The  same  is  true  of  sirups, 
honey,  and  other  sweet  foods.  While  they  are  very  palat- 
able, they  are  also  very  nourishing,  so  that  the  energy 
available  for  the  system  is  greatly  increased  by  their 
consumption. 

Food  value  of  candy.  Candy  is  generally  eaten  between 
meals  without  any  thought  of  its  food  value.  The  grati- 
fication of  the  taste  is  frequently  the  only  object  sought, 
with  the  result  that  the  system  is  overloaded  and  more  or 
less  serious  consequences  follow.  This  is  more  likely  to 
happen  on  account  of  the  very  high  calorific  value  of  many 
constituents  of  candy.  While  glucose  with  1777  calories 
has  the  same  calorific  value  as  sugar,  chocolate  has  a  much 
higher  value ;  that  is,.  2864  calories  per  pound.  Nuts  have 
a  similar  value,  peanuts,  for  example,  giving  2560  calories. 

101 


)M(?§^ --':;;;.  BUEE  FOODS 

Compared  with  these  values,  we  find  that  the  average  value 
for  meats  is  about  1000  calories,  while  vegetables  and  fish 
seldom  give  more  than  500  calories. 

Adult  ration  of  candy  and  nuts.  Candy  must  therefore 
be  looked  upon  as  one  of  our  most  highly  concentrated  and 
nourishing  foods.  This  is  strikingly  illustrated  by  the  fact 
that  one  and  two-thirds  pounds  of  chocolate  creams  give 
3000  calories  of  energy,  the  equivalent  of  a  day's  ration 
for  an  active  adult.  As  chocolate  creams  are  composed 
almost  entirely  of  carbohydrates,  they  would  constitute  a 
very  poorly  balanced  ration.  If  part  of  the  candy  were  re- 
placed by  peanuts,  another  highly  concentrated  food  which 
is  largely  consumed  between  meals,  a  better  balanced  ration 
would  be  obtained.  The  following  table  gives  the  com- 
position of  a  daily  ration  containing  two  thirds  of  a  pound 

TABLE  XX 

Adult  Ration  composed  of  Two  Thirds  of  a  Pound  of  Choc- 
olate Creams  and  Two  Thirds  of  a  Pound  of  Peanuts 


Peanuts 

Chocolate 
creams 

Total 

Calories 

1774 

1200 

2974 

Grains 

Grams 

Grams 

Protein 

75 

7 

82 

Fats 

110 

26 

136 

Carbohydrates     .... 

73 

220 

293 

of  peanuts  and  two  thirds  of  a  pound  of  chocolate  creams. 
It  is  evident  that  not  only  are  the  required  number  of 
calories  of  energy  obtained,  but  that  the  proper  proportion 
between  protein,  fats,  and  carbohydrates  is  maintained  in 
this  small  amount  of  two  articles  generally  eaten  at  odd 
times  merely  to  indulge  the  sense  of  taste. 


CANDIES  103 

Such  a  diet  would  not  be  desirable,  because  all  of  the 
carbohydrates  would  be  present  in  very  soluble  form,  a  con- 
siderable portion  of  which  should  be  replaced  by  starch. 

Candy  not  a  sustaining  food.  The  fact  that  a  taste  for 
candy  does  not  have  to  be  acquired,  but  that  every  one  has 
a  natural  appetite  for  such  food,  undoubtedly  has  a  physio- 
logical explanation.  This  natural  taste  would  seem  to  in- 
dicate a  demand  of  the  system  for  these  very  nourishing 
foods.  The  appetite  seems  to  say,  "  Here  is  a  food  ready 
for  use  which  can  give  me  a  great  deal  of  energy  very 
quickly."  It  is  not,  however,  a  sustaining  food.  One  does 
not  feel  satisfied  for  any  considerable  length  of  time,  as 
after  eating  an  ordinary  dinner.  It  goes  into  the  blood 
quickly  and  is  soon  used  up.  Starch  is  a  much  better  food, 
because  it  is  digested  more  slowly,  giving  the  system 
nourishment  as  it  is  required.  Peanuts  also  could  not  be 
eaten  continually  in  large  quantities,  on  account  of  the 
presence  of  some  constituent  in  small  quantity  which  the 
system  does  not  tolerate.  It  is  evident,  however,  that  sweet- 
meats have  a  very  high  food  value  and  should  not  be  eaten 
in  large  quantities  in  addition  to  the  ordinary  meals,  neither 
should  they  be  eaten  to  the  exclusion  of  the  former. 

Sugars  present  in  candy.  The  manufacture  of  sugar  and 
glucose,  which  constitutes  the  larger  part  of  most  candy, 
has  been  described  in  the  preceding  chapter.  Sugar  con- 
sists mainly  of  one  substance,  sucrose,  represented  by  the 
chemical  formula  C12H22OJJ.  Glucose  is  a  mixture  of  a 
number  of  chemical  compounds,  although  dextrose,  mal- 
tose, and  dextrine  are  the  important  constituents.  Maltose 
has  about  the  same  formula  as  sucrose,  Ci2H220;ij  •  HgO. 
Dextrose  has  the  formula  CqH^^^q,  while  dextrine  is  repre- 
sented by  the  simpler  formula  CgHj^Og.  When  sugar  is 
heated  in  the  presence  of  an  acid,  the  sucrose  is  broken 


104  PURE  FOODS 

down  into  two  constituents,  dextrose  and  levulose.  These 
compounds  are  very  similar  to  glucose  in  their  properties. 
In  making  candy,  therefore,  very  nearly  the  same  result 
maybe  obtained  by  using  a  combination  of  sugar  and  glucose, 
or  by  simply  boiling  sugar  with  an  appropriate  acid,  such 
as  tartaric.  The  same  decomposition  takes  place  in  the 
stomach  when  sugar  is  digested.  There  is  very  little  candy 
made  from  pure  sugar  without  glucose.  These  two  con- 
stituents are  equally  wholesome  and  nutritious.  While 
glucose  is  transparent  and  absolutely  colorless  when  pro- 
duced, it  very  soon  begins  to  turn  light  yellow.  The  candy 
made  from  glucose  is  also  not  pure  white.  This  difficulty 
is  entirely  avoided  by  the  addition  of  a  small  amount  of 
sulphurous  acid  to  the  glucose  or  the  candy.  Until  recently 
this  was  the  common  practice  in  the  manufacture  of  candy 
and  glucose.  It  has  been  largely  discontinued  on  account 
of  the  widespread  belief  that  sulphurous  acid  is  unwhole- 
some, and  the  enactment  of  laws  forbidding  its  use  in 
articles  of  food. 

Sulphurous  acid  injurious.  On  account  of  the  small 
amounts  of  sulphurous  acid  ordinarily  used  in  foods,  no 
immediate  ill  effects  can  usually  be  observed  from  consum- 
ing food  containing  it.  It  has  been  shown,  however,  that 
the  continual  consumption  of  such  foods  tends  ultimately 
to  produce  disease,  especially  of  the  kidneys,  through  which 
the  acid  must  be  eliminated.  There  is  also  the  danger  that, 
if  its  use  in  foods  is  allowed,  excessive  amounts  will  occa- 
sionally be  added  by  careless  or  unscrupulous  manufac- 
turers, subjecting  the  consumer  to  very  serious  danger. 
Formerly  sulphuric  acid  was  very  largely  used  in  the  man- 
ufacture of  glucose.  This  acid  was  neutralized  with  lime, 
producing  calcium  sulphate,  some  of  which  remained  in 
the  glucose.   While  there  is  more  objection  to  the  presence 


CAKDIES 


105 


Copyrijrht,  Underwood  &  Underwood,  N.Y. 

Fig.  21.   The  Cocoa  Tree,  showing  the  Fruit  growing  on  the  Trunk 

of  this  compound  than  to  the  presence  of  the  salt  which 
remains  in  the  glucose  as  made  at  present  with  hydro- 
chloric acid,  it  cannot  be  said  that  calcium  sulphate  is 
injurious  in  moderate  amounts.    This  is  evident  from  the 


106  PURE  FOODS 

fact  that  almost  all  natural  waters  used  for  drinking  con- 
tain this  substance. 

Food  value  of  chocolate  creams.  Chocolate  is  another 
very  common  constituent  of  candy.  In  the  United  States 
chocolate  creams  are  the  most  popular  and  largely  sold  of 
all  candies.  The  popular  taste  in  this  instance  seems  to 
have  a  correct  physiological  basis,  since  chocolate  creams 
contain  all  the  elements  of  a  complete  diet,  namely  fats, 
protein,  and  carbohydrates.  The  flavoring  matter  of  the 
chocolate  is  also  very  agreeable  to  most  palates. 

History  of  cocoa.  Chocolate  is  made  from  the  cocoa  bean, 
which  grows  on  a  tree  which  is  indigenous  to  Central 
America.  It  was  discovered  by  Cortes  during  his  conquest 
of  Mexico.  The  Mexicans  had  cultivated  the  tree  and  used 
the  bean  in  much  the  same  manner  as  we  do  at  present. 
Cortes  introduced  its  use  into  Spain,  where  it  soon  became 
very  popular.  From  Spain  its  use  spread  to  Italy,  thence 
to  France  and  to  England.  The  young  American  colonists 
learned  its  use  from  the  mother  country,  and  as  the  people 
of  the  United  States  have  prospered,  the  consumption  of 
the  products  of  the  cocoa  bean  have  steadily  and  rapidly 
increased,  in  spite  of  the  fact  that  its  use  is  generally  con- 
sidered a  luxury.  The  botanist  Linnaeus  gave  it  its  name 
Theohroma  cacao,  Theohroma  means  ''food  of  the  gods,"  and 
undoubtedly  was  designed  to  express  Linnseus'  opinion  of 
the  delicate  flavor  of  the  bean.  The  word  "cacao"  is  the 
Mexican  name  of  the  plant. 

The  cocoa  tree.  This  tree  flourishes  both  wild  and  culti- 
vated in  warm  moist  climates,  such  as  Mexico  and  Central 
America,  parts  of  South  America,  and  other  tropical  regions. 
It  grows  best  in  sheltered  valleys  where  a  soft  rich  soil  is 
kept  moist  by  a  neighboring  river,  and  where  it  is  sheltered 
by  other  and  taller  trees.  Under  these  conditions  it  blossoms 


CAKDIES 


107 


throughout  the  entire  year.  It  has  red  flowers,  which  develop 
into  a  yellow  fruit,  about  one  thousand  flowers  being  required 
to  produce  a  single  fruit.  This  is  large,  about  10  inches 
long  by  4  inches  wide.  The  soft  pulp  surrounds  from  25 
to  40  seeds,  which  are  the  cocoa  beans  of  commerce.  The 
fruit  ripens  at  all  times  of  the  year,  as  is  customary  with 
tropical  vegetation.  The  fruit  is  cut  off  the  tree,  split 
open,  and  the  beans  removed,  and  in  some  localities  dried 


r- 
\ 

i 

m.m-i 

ms^ 

IR'?'"  ■■■•  ■-*:-^'::; 

*> 

J 

1 

TM 

■-  ^^^"%'-'^  i 

^i 

^4liP 

'  /-, 

■u 

^^M 

Fig.  22.   Gathering  the  Cocoa  Fruit 

immediately  in  the  sun.  The  better  grades  are  first  sub- 
jected to  a  fermentation  process,  which  destroys  certain 
bitter  constituents. 

Roasting  the  beans.  The  flavor  and  other  properties  of 
the  beans  differ  with  the  country  in  which  they  are  grown. 
By  carefully  selecting  and  mixing  different  varieties  of 
beans  the  best  flavored  chocolate  is  produced.  When  the 
beans  are  first  brought  to  the  factory,  sticks,  stones,  and 
dust  must  be  removed  and  the  beans  sorted  to  even  sizes. 
The  next  process  is  the  roasting  of  the  bean.    This  is  done 


108  PUEE  FOODS 

by  placing  the  raw  beans  in  a  steel  cylinder,  which  is  heated 
and  revolved  until  the  beans  are  uniformly  roasted.  The 
roasting  develops  the  odor  and  flavor  of  the  beans,  gives 
them  a  brown  color,  and  removes  the  stringent  taste  of  the 
raw  bean. 

Cocoa  hulls.  The  roasted  beans  are  next  placed  in  a 
machine  in  which  the  hulls  are  broken  off  and  blown  away. 
In  the  next  operation  the  beans  are  crushed  and  the  radical 
removed.  The  radical  is  a  small  germ  from  which  the  plant 
grows  when  the  bean  is  allowed  to  sprout.  About  16  per 
cent  of  the  weight  of  the  bean  is  lost  in  roasting  and  hull- 
ing, some  of  which  is  due  to  loss  of  moisture.  A  little  of 
the  fat  also  goes  into  the  hulls,  which  contain  5  per  cent  of 
fat  and  about  0.8  per  cent  of  theobromine.  When  boiled  in 
water  a  liquid  is  obtained  which  has  some  of  the  properties 
of  cocoa,  but  is  of  very  little  value  as  such.  The  hulls 
have  been  largely  used  as  an  adulterant.  For  this  purpose 
they  are  ground  and  mixed  with  cocoa,  spices,  etc.  They 
have  some  value  as  cattle  food. 

Cocoa  butter.  The  meats  of  the  beans,  known  as  cocoa 
nihs^  are  next  ground  in  stone  mills.  There  are  usually  three 
mills  in  a  set,  so  that  the  beans  are  ground  three  times. 
This  reduces  them  to  a  thin  paste,  which  is  known  as 
unsweetened  chocolate,  and  which  on  cooling  becomes  a 
hard  cake.  It  contains  about  50  per  cent  of  fat.  From  40 
to  50  per  cent  of  this  fat  may  be  removed  by  subjecting 
the  chocolate  to  moderate  pressure  in  a  hydraulic  press, 
while  if  subjected  to  a  pressure  of  4500  pounds  per  square 
inch,  60  per  cent  of  the  fat  may  be  removed.  This  fat  is  solid 
at  the  ordinary  temperatures  and  is  known  as  cocoa  butter. 
It  is  used  to  a  considerable  extent  in  pharmaceutical  and 
medical  preparations,  but  most  largely  in  the  preparation 
of  chocolate  bars  and  the  chocolate  coating  of  candy. 


■f  ^^f ^^^j(k 

mm 

109 


110  PURE  FOODS 

Breakfast  cocoas.  These  are  prepared  by  grinding  to  a 
powder  the  chocolate  from  which  a  portion  of  the  cocoa 
butter  has  been  pressed  out.  The  amount  of  fat  remaining 
in  the  cocoa  varies  with  the  different  brands.  All  of  the 
fat  contained  in  the  chocolate  cannot  be  allowed  to  remain, 
because  the  resulting  cocoa  Avould  be  too  rich  and  indi- 
gestible for  most  people.  As  from  40  to  60  per  cent  of  the 
cocoa  butter  is  removed  by  means  of  hydraulic  pressure, 
cocoa  will  contain  from  28  to  38  per  cent  of  fat,  while 
unsweetened  chocolate  contains  50  per  cent.  In  the  prep- 
aration of  some  of  the  brands  the  cocoa  is  treated  in  such 
a  manner  that  the  fat  which  remains  is  more  readily  emulsi- 
fied by  water.  By  the  Dutch  process  the  cocoa  is  treated 
with  hot  water  and  alkalies,  such  as  potassium,  sodium,  or 
magnesium  carbonate.  In  the  German  process  ammonia 
or  ammonium  carbonate  is  used.  This  results  in  the  pro- 
duction of  a  purer  cocoa,  as  in  the  subsequent  roasting  the 
ammonium  compounds  are  entirely  expelled,  while  the 
soda,  potash,  or  magnesia  introduced  by  the  Dutch  process 
remain  in  the  finished  cocoa.  The  presence  of  these  con- 
stituents may  be  desirable  for  some  people,  while  they 
could  never  be  considered  injurious.  After  a  treatment  of 
this  kind  the  cocoa  is  powdered  and  is  ready  for  use.  The 
treatment  with  the  alkalies  has  changed  the  cocoa  in  such 
a  way  that  it  remains  suspended  when  boiled  with  water  or 
milk,  and  does  not  so  readily  settle  to  the  bottom  of  the 
vessel.  The  fat  of  the  cocoa  is  also  very  probably  rendered 
more  easily  digestible.  Breakfast  cocoa  also  contains  from 
6  to  24  per  cent  of  proteids  as  well  as  from  14  to  28  per  cent 
of  starch  and  fiber  (Table  XXI,  p.  112).  Cocoa,  therefore, 
contains  all  the  constituents  of  a  complete  diet  in  quite  large 
proportions.  As  the  amount  of  water  is  small  and  proteids 
are  generally  expensive,  cocoa  is  also  a  relatively  cheap  food. 


Ill 


112 


PURE  FOODS 


Composition  of  breakfast  cocoas.  The  following  table  gives 
the  composition  of  a  number  of  the  well-known  brands  of 
breakfast  cocoa  on  the  market  to-day : 


TABLE  XXI 

Composition  of  Breakfast  Cocoas 


Brand 

Water 

Ash 

Fat 

Theo- 
bromine 

Starch, 
fiber,  etc. 

Protein 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Huyler      .... 

4.27 

5.54 

34.04 

1.02 

18.70 

■  17.29 

Miller 

3.99 

4.05 

38.76 

1.06 

24.17 

6.77 

I'ry 

4.33 

4.28 

31.16 

1.36 

28.23 

12.78 

Walter  Baker  .    . 

6.02 

4.70 

29.30 

1.28 

14.66 

19.53 

Van  Houten  (Dutch) 

4.53 

8.19 

29.78 

0.69 

29.96 

17.03 

Bensdorp  (Dutch) 

4.59 

6.69 

33.06 

0.88 

19.85 

11.41 

Wilbur     .... 

3.84 

4.69 

33.32 

0.82 

22.78 

16.74 

Cadbury  .... 

4.00 

4.70 

27.58 

0.70 

27.53 

13.58 

Whitman      .    .    . 

2.70 

4.15 

37.68 

0.66 

20.36 

14.13 

Lowney    .... 

3.20 

5.43 

23.00 

17.68 

24.88 

The  large  amount  of  ash  in  the  Van  Houten  and  Bens- 
dorp brands,  which  are  Dutch  cocoas,  is  due  to  the  presence 
of  the  alkalies  introduced  in  the  process  of  manufacture. 
It  is  evident  that  cocoa  contains  a  great  deal  of  nourish- 
ment, and  that  the  beverage,  especially  when  prepared  with 
milk,  has  a  high  nutritive  value  in  addition  to  the  stimu- 
lating properties  given  to  it  by  the  theobromine  and  caffeine. 
Coffee  and  tea  have  similar  stimulating  properties  but  very 
little  food  value. 

Adulteration  of  cocoa.  While  the  removal  of  a  portion 
of  the  fat  of  the  chocolate  for  the  manufacture  of  cocoa  is 
desirable,  the  tendency  is  to  reduce  the  amount  of  this  con- 
stituent to  the  least  that  is  acceptable  to  the  public,  on 
account  of  the  high  price  and  great  demand  for  the  cocoa 


bo 

o 


113 


114 


PURE  FOODS 


butter.  Cocoa  is  also  easily  adulterated  by  the  addition 
of  the  ground  hulls,  which  have  very  little  food  value  and 
little  or  no  commercial  value. 

Chocolate.  This  is  the  name  by  which  the  ground  cocoa 
bean  from  Avhich  no  fat  has  been  removed,  is  known.  It  is 
used  pure  and  mixed  with  cocoa  butter  and  sugar.  The 
quantity  of  sugar  varies  from  50  to  70  per  cent,  while  about 
24  per  cent  of  fat  must  be  present.  Its  composition  and 
that  of  chocolate  creams  is  given  in  the  following  table : 

TABLE  XXII 

Composition  of  Chocolate  and  Peanuts 


Peanuts 

Chocolate 

Choco- 
late 

CREAMS 

Pure 

Sweet 

Calories 

2560 

2860 

2131 

1800 

Carbohydrates 

Sugar  

Starch 

Fat 

Proteids 

Theobromine      

Caffeine      

Fiber . 

Ash 

Per  cent 
25 

38 
26 

2 
9 

Per  cent 
27.6 

50 
12 

1 

0.4 

3 

3 

3 

Per  cent 

57 
9.2 

16.7 
4.0 
0.4 
0.1 
1.0 
1.0 

10.6 

Per  cent 

79.4 
2.76 
5.00 
1.2 
0.1 
0.04 
0.3 
0.3 

Water 

10.6 

It  is  evident  from  the  table  that  the  addition  of  sugar  ren- 
ders'chocolate  a  better  food  because  the  unmixed  product 
contains  a  larger  percentage  of  fat  than  most  people  can 
readily  assimilate.  The  addition  of  the  sugar  very  mate- 
rially reduces  the  percentage  of  protein.  This  element  can 
readily  be  supplied  by  other  foods. 


M 


o 
O 

.9 
o 


115 


116  PURE  FOODS 

Chocolate  creams.  In  the  manufacture  of  chocolate 
creams,  cocoa  butter  is  added  to  the  chocolate  in  order  to 
give  the  glossy  appearance  to  the  coating.  The  interior  of 
the  cream  is  composed  of  sugar  and  glucose,  although 
various  fruit  jellies,  nuts,  etc.,  are  dipped  in  chocolate  in 
order  to  give  variety  to  the  candy.  Fig.  28  shows  a  part 
of  this  process.  On  the  right  are  seen  double  boilers  in 
which  the  fondant  is  mixed  with  flavoring  matter;  on 
the  left  are  seen  the  automatic  molding  machines  wherein 
the  fondant  is  cast  in  molds  before  being  coated  with  choc- 
olate. A  large  number  of  chocolate  preparations  have  been 
made  and  sold,  such  ingredients  as  milk,  cream,  malt, 
oatmeal,  nuts,  etc.,  being  used.  Plain  chocolate  in  bars, 
containing  60  per  cent  of  sugar  and  40  per  cent  of  choco- 
late, is  very  popular  in  Europe.  A  thin  coat  of  shellac 
varnish  is  very  commonly  used  on  chocolate  and  other 
candies  in  order  to  form  a  hard  protective  coating  and 
prevent  the  candy  from  absorbing  moisture  and  sticking 
together. 

Adulteration  of  chocolate.  Chocolate  has  been  subjected 
to  considerable  adulteration.  In  the  first  place,  the  rather 
expensive  cocoa  butter  has  been  replaced  with  various 
cheaper  fats,  such  as  beef  stearin  and  coconut-oil  stearin. 
A  bean  known  as  St.-John's-bread  is  sometimes  ground 
and  mixed  with  chocolate.  This  bean  is  quite  sweet  and 
has  a  fairly  agreeable  odor.  A  still  more  reprehensible 
practice  consists  in  making  an  imitation  chocolate  from  a 
mixture  of  iron  oxide,  gelatin,  and  sugar.  The  iron  oxide 
is  dark  red  and  resembles  the  chocolate  very  closely.  The 
gelatin  gives  the  proper  consistency  to  the  mixture,  and 
the  gloss  produced  by  the  fat  of  true  chocolate  is  imitated 
by  a  coating  of  shellac  varnish.  If  the  color  of  the  choco- 
late cannot  be  matched,  a  little  aniline  dye  is  added. 


117 


118  PUEE  FOODS 

Use  of  eggs  in  candy.  A  considerable  number  of  other 
substances  are  used  in  small  amount  in  candies.  Among 
these  are  eggs.  Since  on  account  of  natural  causes,  a  large 
proportion  of  the  eggs  produced  are  obtained  during  the 
spring  and  summer  months,  while  the  consumption  of  this 
excellent  food  is  distributed  quite  uniformly  throughout 
the  year,  considerable  difficulty  is  experienced  in  obtain- 
ing a  supply  of  fresh  eggs  at  all  times.  The  candy  manu- 
facturer can  quite  easily  utilize  eggs  preserved  in  such 
manner  that  they  could  not  be  sold  to  the  ordinary  con- 
sumer. Dried  eggs  are  very  convenient  for  the  manufac- 
turer. In  countries  where  the  supply  exceeds  the  demand, 
the  contents  of  the  egg  are  removed  from  the  shell  and 
the  yolk  and  white  separated  and  dried.  The  yolk  pro- 
duces a  powder ,  while  the  white  produces  flakes.  As  no 
portion  of  the  food  value  of  the  egg  is  lost  in  this  process, 
there  can  be  no  objection  to  the  use  of  dried  eggs,  provided 
the  process  is  carried  out  in  a  sanitary  manner.  At  times, 
however,  boric  acid  or  other  preservative  is  introduced, 
which  remains  in  the  candy.  A  still  more  reprehensible 
practice  consists  in  the  transportation  of  the  broken  eggs 
in  the  liquid  state  preserved  with  boric  acid  or  formalde- 
hyde. This  practice  has  been  largely  prevented  by  the 
efforts  of  the  pure-food  authorities. 

Gelatin.  Eggs  may  be  entirely  replaced  in  candies  by 
gelatin,  which  is  considerably  cheaper.  Aside  from  its  low 
nourishing  properties,  there  can  be  no  objection  to  this 
practice  if  a  good  grade  of  pure  gelatin  is  used. 

Coloring  matter.  This  is  very  largely  used  in  candies. 
While  it  is  considered  fraudulent  to  color  or  dye  many 
food  products,  this  is  not  true  in  general  of  candies.  If 
some  substance  is  colored  to  imitate  chocolate,  and  thereby 
deceive   the   consumer,    it   would    be   considered   illegal. 


110 


120 


CANDIES  121 

There  is  no  attempt  at  deceit,  however,  in  coloring  most 
candies.  Consumers  are  generally  aware  that  the  coloring 
matter  is  added  merely  to  please  the  eye.  It  is  very  essen- 
tial, however,  that  the  dye  used  shall  be  absolutely  harm- 
less.   This  question  will  be  discussed  in  the  next  chapter. 

Flavoring  matter  of  all  kinds  is  also  used  in  large  quan- 
tities in  candies.  The  same  requirement  holds  good  here 
that  the  flavoring  matter  must  be  wholesome.  This  subject 
is  fully  discussed  in  Chapter  XVIII. 

EXPERIMENT 

26.  Detection  of  glucose.  As  glucose  contains  a  considerable  amount 
of  dextrin,  which  is  insoluble  in  methyl  alcohol,  the  presence  of 
glucose  in  candy  and  other  foods  may  be  tested  for  in  a  very  simple 
manner.  A  concentrated  solution  of  the  candy  is  made  by  dissolv- 
ing the  sample  in  two  or  three  times  its  volume  of  water.  The  solu- 
tion is  allowed  to  settle,  or  is  filtered  if  insoluble  matter  is  present. 
On  adding  methyl  alcohol  (wood  alcohol)  with  constant  stirring,  a 
heavy  white  precipitate  indicates  the  presence  of  glucose.  Gelatin 
and  soluble  starch  would  also  be  precipitated  by  the  alcohol. 

Sirups,  honey,  etc.,  may  be  examined  for  the  presence  of  corn 
sirup  in  the  same  manner.  The  sample  is  diluted  with  an  equal 
volume  of  water  and  the  methyl  alcohol  added. 


CHAPTER   XI 

ANILINE   DYES   AND  OTHER   FOOD   COLORS 

Fraudulent  coloring  of  foods.  The  artificial  coloring  of 
foods  has  been  very  generally  regarded  as  a  fraudulent  prac- 
tice. The  color  and  general  appearance  of  many  foods  is 
so  commonly  used  as  a  criterion  of  quality  and  condition 
that  any  attempt  to  alter  the  natural  appearance  by  the 
introduction  of  foreign  coloring  matter  at  once  arouses  the 
suspicion  that  an  attempt  is  being  made  to  cover  defects 
and  to  deceive  the  consumer  into  thinking  that  the  food  in 
question  is  better  than  it  actually  is.  Coloring  matter  is 
frequently  introduced  in  order  to  create  the  impression 
that  a  given  constituent  is  present  when  it  is  entirely 
absent.  A  common  instance  of  this  practice  is  the  use  of 
yellow  coloring  matter  in  cakes  as  a  substitute  for  eggs. 
Such  coloring  matter  has  been  sold  to  bakers  under  such 
names  as  "  egg  substitute,"  etc.  When,  in  addition  to  these 
obviously  fraudulent  practices,  the  fact  is  taken  into  con- 
sideration that  aniline  dyes  have  been  very  extensively 
used  in  foods,  and  that  many  of  these  compounds  are  ex- 
tremely poisonous,  the  opposition  to  the  use  of  any  color- 
ing matter  whatever  in  foods  seems  fully  justified. 

Harmless  coloring.  It  has  been  shown,  however,  in  the 
chapter  on  candies,  that  the  introduction  of  coloring  matter 
into  sweetmeats  does  not  deceive  the  public.  In  other  cases 
the  statement  on  the  label  of  a  food  that  it  has  been  artifi- 
cially colored  would  remove  in  a  large  measure  the  objec- 
tions to  the  practice.    Of  course  no  coloring  matter  which 

122 


ANILINE  DYES  AND  OTHER  FOOD  COLORS     123 

is  at  all  poisonous  should,  under  any  circumstances,  be 
introduced  into  foods. 

Vegetable  colors.  Two  classes  of  coloring  matter  have 
been  used  in  foods,  namely  vegetable  colors  and  aniline 
dyes.  The  former  are  obtained  by  extracting  the  natural 
coloring  matter  from  some  portion  of  a  given  plant.  The 
wood  of  a  number  of  tropical  trees  has  been  largely  used 
for  this  purpose,  such  as  barbary,  Brazil,  fustic,  Lima,  and 
saffron.  In  this  class  is  generally  included  the  dye  cochineal, 
which  is  obtained  from  a  bug  which  is  collected  and  dried 
in  Mexico  and  other  tropical  countries.  Butter  was  for- 
merly often  colored  on  the  farm  by  means  of  the  yellow 
color  extracted  from  carrots. 

The  aniline  dyes,  on  the  other  hand,  are  produced  from 
compounds  which  are  distilled  out  of  coal  tar  and  combined 
with  various  chemical  reagents. 

Poisonous  vegetable  colors.  While  it  would  seem  that 
the  vegetable  colors  would  be  more  wholesome  than  the 
coal-tar  dyes,  this  cannot  be  assumed,  because  some  of  the 
most  violent  poisons  known  are  obtained  from  vegetables. 
Only  when  the  color  is  obtained  from  a  vegetable  which  is 
known  to  be  wholesome  can  this  be  assumed.  The  vegetable 
colors  lack  the  brilliancy  and  high  tinting  power  of  the 
mineral  colors,  and  are  also  far  less  permanent,  so  that  in 
many  cases  they  are  destroyed  when  put  into  food  which 
is  boiled  for  any  length  of  time.  Attempts  have  been  made 
to  render  these  more  permanent  by  the  introduction  of 
mineral  constituents  such  as  sulphuric  acid.  In  such  proc- 
esses mineral  poisons  are  liable  to  be  introduced,  so  that 
vegetable  colors  treated  in  this  manner  must  be  considered 
as  partly  mineral  in  character. 

Poisonous  aniline  dyes.  Aniline  dyes  may  be  poisonous 
for  several  reasons,  which  must  be  clearly  differentiated. 


124  PUEE  FOODS 

In  the  first  place,  the  chemical  compound  which  gives  the 
color  may  be  poisonous.  On  the  other  hand,  if  this  is  harm- 
less, the  dye  as  manufactured  and  sold  may  be  poisonous, 
because  other  poisonous  substances  introduced  in  the  proc- 
ess of  manufacture  may  not  have  been  entirely  eliminated. 
Among  such  substances,  arsenic  is  the  most  common.  This 
element  is  very  widely  distributed  in  the  earth,  so  that  it  is 
present  in  small  amount  in  a  great  many  chemical  com- 
pounds unless  the  greatest  care  has  been  taken  to  eliminate 
it.  If  such  a  compound  has  been  used  in  the  manufacture 
of  a  given  dye,  some  or  all  of  the  arsenic  may  remain  in  the 
dye.  For  a  great  many  purposes  for  which  aniline  dyes  are 
used,  the  presence  of  a  small  amount  of  arsenic  is  not 
objectionable.  Dyes  which  are  designed  for  food  purposes 
must  be  entirely  free  from  this  element.  The  manufacture 
of  aniline  dyes  which  are  entirely  free  from  arsenic  requires 
the  very  greatest  technical  skill  and  care,  which  tends  to 
greatly  increase  the  cost  of  such  dyes.  The  color  of  many 
dyes  is  rendered  more  brilliant  or  changed  in  shade  if  the 
dye  is  allowed  to  combine  with  a  metallic  compound.  As 
many  of  the  metals  form  poisonous  compounds,  dyes  treated 
in  this  manner  cannot  be  used  for  food  purposes. 

Methods  of  proving  dyes  harmless.  A  great  many  experi- 
ments have  been  conducted  on  pure  aniline  dyes  which 
contained  no  poisonous  impurities,  to  ascertain  if  the  dye 
itself  is  poisonous  or  harmless.  Such  experiments  have 
been  carried  out  in  various  ways.  Small  animals  such  as 
rabbits  and  dogs  have  been  fed  with  food  containing  the 
dye  being  tested.  The  effect  on  the  animals  was  carefully 
noted,  the  dye  being  fed  in  varying  amounts  and  for  long 
periods  of  time,  if  it  proved  to  be  comparatively  harmless. 
In  the  latter  case  experiments  have  been  carried  out  on 
human  beings.    In  the  case  of  poisonous  dyes  a  record  has 


ANILINE  DYES  AND  OTHER  FOOD  COLORS     125 

been  made  of  cases  in  which  such  dyes  have  been  taken  by 
human  beings  by  mistake  or  with  suicidal  intent.  Investi- 
gations have  also  been  conducted  as  to  the  health  of  work- 
men employed  in  factories  where  dyes  are  manufactured. 
Such  workmen  are  liable  to  inhale  dust  containing  the  dye, 
or  to  take  food  or  drink  containing  small  quantities  of  it. 

Experiments  with  a  poisonous  dye.  The  following  experi- 
ments indicate  the  character  of  the  evidence  obtained  in 
this  manner.  Experiments  with  dinitrocresol  or  saffron 
substitute  resulted  as  follows :  0.25  gm.  was  administered 
to  rabbits.  The  respiration  became  rapid  and  the  animals 
soon  fell  to  the  ground.  Spasms  followed,  and  finally  death 
in  from  twenty  to  thirty  minutes.  Dogs  died  with  similar 
symptoms  from  doses  as  small  as  0.1  gm.  A  woman  died 
in  five  hours  after  taking  4.5  gm.  of  saffron  substitute. 
This  dye  is  clearly  a  very  dangerous  poison. 

Experiments  with  a  harmless  dye.  The  following  experi- 
ments were  carried  out  with  fuchsin.  Two  rabbits  were 
fed  ^  gm.  of  the  dye  in  50  gm.  of  barley  daily  for  sev- 
eral weeks  without  showing  any  bad  effects  whatever.  Other 
rabbits  were  fed  15  gm.  of  the  dye  in  15  gm.  of  barley 
for  two  weeks  without  showing  any  ill  effects.  One  per 
cent  solutions  of  the  dye  were  injected  directly  into  the 
blood  of  rabbits  without  showing  any  ill  effects.  Dogs  were 
fed  20  gm.  daily,  while  a  man  took  3^  gm.  in  a  week 
without  showing  any  ill  effects.  An  investigation  of  the 
health  of  52  workmen  employed  in  a  fuchsin  factory  gave 
the  following  results:  No  ill  health  could  be  observed 
among  the  workmen,  although  six  had  been  employed  for 
three  to  four  years,  six  for  four  to  six  years,  eleven  for 
six  to  ten  years,  and  five  for  eleven  to  eighteen  years.  It 
was  concluded  from  the  experiments  that  fuchsin  could  be 
safely  employed  as  a  food  color. 


126  PURE  FOODS 

Dyes  permitted  by  the  United  States  Department  of  Agri- 
culture. This  department  has  prepared  a  list  ^  of  the  aiiiHne 
dyes  which  have  been  shown  to  be  absolutely  harmless.  I 
The  use  of  other  aniline  dyes  in  foods  is  illegal,  and  the  i 
dyes  which  are  allowed  must  be  free  from  any  other  color- 
ing matter  as  well  as  from  any  contamination  due  to  imper- 
fect or  incomplete  manufacture.  The  use  of  these  dyes  is 
also  illegal  when  the  object  sought  is  to  conceal  damage 
or  inferiority. 

Amount  of  dyes  used  in  food.  The  amount  of  dye  com- 
monly used  in  foods  is  very  small,  so  that  only  minute 
amounts  are  ordinarily  consumed  by  a  single  individual. 
One  ounce  is  generally  sufficient  to  color  from  twenty-five 
to  thirty-five  pounds  of  candy.  This  accounts  for  the  fact 
that  a  relatively  small  number  of  cases  of  serious  poisoning 
have  occurred  during  the  many  years  when  manufacturers 
were  under  very  little  restraint  as  to  the  dyes  which  were 
used. 

Harmless  vegetable  dyes.  A  number  of  vegetable  colors 
are  in  common  use  and  are  entirely  harmless.  Among  these 
are  turmeric,  cochineal,  annatto,  indigo,  litmus,  and  saffron. 

The  tests  for  aniline  and  vegetable  dyes  are  given  in 
Chapter  XIII. 

1  Food  Inspection  Decision  76.  The  list  contains  seven  dyes  as  follows : 
The  numbers  are  given  as  listed  in  A.  G.  Green's  edition  of  the  Schultz-Julius 
Systematic  Survey  of  the  Organic  Coloring  Matters  (1904).  The  list  is  as 
follows : 

Red  shades  Yellow  shade 

107.  Amaranth  4.  Naphthol  yellow  S. 

56.  Ponceau  3  R.  Green  shade 

517.  Erythrosin  435.  Light  green  S.  F.  yellowish 

Orange  shade  Blue  shade 

85.  Orange  I.  692.  Indigo  disulfoacid 

This  list  was  prepared  for  the  Department  of  Agriculture  by  Dr.  Bernhard 
C.  Hesse  of  New  York  City,  who  is  an  expert  on  dyes. 


CHAPTER  XII 

PRESERVATION  OF  FOODS 

Modern  people  well  fed.  The  certainty  and  regularity 
with  which  modern  civihzed  man  is  supplied  with  his  daily 
food  would  have  astonished  and  delighted  the  people  living 
only  a  few  hundred  years  ago.  Famine  can  no  longer  exist 
except  among  savages  and  in  semicivilized  countries.  Civi- 
lized man  not  only  expects  a  bounteous  supply  of  all 
staple  foods,  but  demands  a  regular  supply  of  dainties  and 
luxuries  at  all  seasons  of  the  year.  No  generation  has  been 
fed  so  well  as  the  people  of  to-day.  This  certainty  of  the 
food  supply  has  rendered  it  possible  for  men  to  give  their 
undivided  attention  to  the  development  of  the  arts  and 
sciences,  and  accounts  in  no  small  measure  for  the  remark- 
able progress  made  in  our  industrial  life,  and  for  the  scientific 
achievements  of  the  age. 

Advantage  of  methods  of  preservation.  The  equal  dis- 
tribution of  all  kinds  of  foods  durmg  all  seasons  through- 
out all  parts  of  civilized  countries  has  been  rendered 
possible  by  the  development  of  the  methods  of  preserva- 
tion and  transportation  of  foods.  Fresh  milk  is  regularly 
shipped  five  hundred  miles.  Poultry,  fish,  and  meats  are 
kept  in  cold  storage  for  many  months.  All  kinds  of  foods 
have  been  successfully  canned  so  as  to  be  preserved  for 
years.  By  the  application  of  hothouse  methods  o.f  horti- 
culture and  rapid  transportation  from  tropical  countries, 
fresh  vegetables  and  fruits  may  be  obtained  almost  equally 
well  at  all  seasons  of  the  year.    Although,  on  the  whole, 

127 


128  PUEE  FOODS 

man  has  benefited  greatly  by  modern  methods  of  preserva- 
tion, it  cannot  be  denied  that  some  harm  has  resulted  from 
the  use  of  preserved  foods,  and  that  some  methods  which 
have  been  used  should  be  condemned. 

Methods  of  preservation  in  use.  The  decomposition  of 
foods  is  almost  entirely  due  to  the  action  of  bacteria,  as  has 
already  been  explained  in  the  chapters  on  milk  and  bac- 
teria, so  that  any  method  of  preservation  of  foods  neces- 
sarily involves  the  destruction  of  the  bacteria  or  arresting 
their  development  and  growth,  or,  what  is  still  better,  pre- 
venting their  entrance  into  food.  The  methods  of  preserva- 
tion of  foods  which  have  been  used  may  be  grouped  into 
four  classes  as  follows : 

1.  Desiccation j  or  drying  so  as  to  reduce  the  percentage 
of  water  to  a  very  small  amount. 

2.  Use  of  low  temperature ;  that  is,  from  10°C.  or60°F. 
to  considerably  below  the  freezing  point. 

3.  Use  of  high  temperatures ;  that  is,  from  about  65°  C. 
or  150°  F.  to  considerably  above  the  boiling  point  of  water 
(about  120°  C.  or  248°  F.). 

4.  The  addition  of  foreign  substances  known  as  preserv- 
atives.  These  may  be  divided  into  two  groups  as  follows : 

a.  Long-used  preservatives,  —  salt,  spices,  sugar,  vinegar, 
alcohol,  smoke,  pyroligneous  acid. 

h.  Modern  chemical  preservatives,  —  borax  or  boric  acid, 
sodium  benzoate  or  benzoic  acid,  sodium  salicylate  or  sali- 
cylic acid,  formaldehyde,  fluorides,  sulphurous  acid  or 
sulphites,  and  hydrogen  peroxide. 

The  proper  use  of  each  method.  All  of  these  methods 
owe  their  efficiency  as  preservatives  to  their  influence  on 
the  life  and  growth  of  bacteria.  We  find  that  these  minute 
organisms  cannot  grow  in  the  absence  of  water,  at  rel- 
atively low  or  high  temperatures,  nor  in  the  presence  of 


PRESERVATION  OF  FOODS  129 

fixed  amounts  of  a  considerable  number  of  various  sub- 
stances. It  is  important  to  know,  with  reference  to  a  given 
method  of  preservation,  not  only  how  the  bacteria  are 
affected,  but  also  what  changes  are  produced  in  the  flavor, 
nutritive  value,  and  digestibility  of  the  food  preserved,  and 
also  whether  the  preservative  itself  is  wholesome  or  not. 
Careful  study  will  show  that  all  methods  of  preservation 
are  not  equally  well  adapted  to  the  preservation  of  a  given 
food.  The  method  chosen  must  not  injure  the  flavor, 
digestibility,  or  appearance  of  the  food.  Boiling,  for  in- 
stance, is  an  excellent  method  of  sterilizing  foods  for  pres- 
ervation, but  it  very  materially  injures  the  flavor  and 
reduces  the  digestibility  of  milk,  while,  on  the  other  hand, 
fruits  and  especially  vegetables  are  in  many  cases  rendered 
much  more  palatable  and  digestible  by  being  cooked. 

Preservation  by  drying.  The  preservation  of  foods  by 
drying  has  been  practiced  from  the  earliest  times,  meats, 
fish,  and  fruits  being  treated  in  this  manner.  In  hot,  dry 
climates  this  process  has  been  extensively  practiced  because 
no  special  precautions  are  needed  to  insure  success.  In  a 
cooler  climate,  especially  during  damp  weather,  the  food  is 
apt  to  ferment  and  decompose  before  it  is  sufficiently  desic- 
cated. To  overcome  this  difficulty  chemical  preservatives 
are  often  added.  In  the  case  of  fruits,  sulphurous  acid  is 
especially  suited  to  this  purpose  because  it  preserves  th© 
color  of  the  fruit,  which  would  otherwise  darken  more  or 
less  during  the  process  of  drying.  Recently  fruits  and 
vegetables  have  been  dried  by  subjecting  them  to  the 
action  of  artificially  dried  and  heated  air.  This  imitates 
the  conditions  found  in  countries  having  a  hot,  dry  climate 
where  no  preservative  is  needed.  In  many  ways  this  is  an 
ideal  method  of  preservation,  as  the  flavor  and  solubility 
of  many  foods  are  but  slightly  affected,  while  such  food  is 


130  PURE  FOODS 

easily  handled  and  transported  and  can  be  kept  in  good 
condition  for  a  very  long  period  of  time.  Recently  such  a 
perishable  food  as  milk  has  been  successfully  dried  and 
reduced  to  a  powder,  which  can  be  redis solved  in  water, 
reproducing  the  liquid  milk. 

Sanitary  conditions  during  drying.  Recent  investigations 
have  shown  that  sufficient  care  is  not  always  taken  in  the 
drying  of  fruits  to  maintain  sanitary  conditions,  and  that 
the  exposure  of  fruits  while  drying  to  flies  and  other  insects 
may  lead  to  the  deposition  of  eggs,  which  develop  into  the 
larvae  of  these  insects  and  render  the  dried  fruit  unfit  for 
human  consumption.  Through  the  rigid  inspection  by  the 
United  States  Department  of  Agriculture  fruits  prepared 
under  such  conditions  are  being  condemned.  A  careful 
examination  of  dried  fruits  before  consumption  is  always 
advisable. 

Refrigeration.  Preservation  by  refrigeration  also  has  the 
advantage  that  no  foreign  substance  is  introduced  into  the 
food,  and  only  slight,  if  any,  changes  brought  about  in  its 
composition  or  flavor.  It  has  the  advantage  over  desiccation 
in  that  the  natural  juices  remain  intact.  This  method  is  ad- 
mirably adapted  to  the  preservation  of  meat,  fish,  vegetables, 
fruits,  poultry,  eggs,  milk,  etc.  The  same  temperature  is 
not  suitable  for  all  of  these  foods,  and  differs  with  the 
length  of  time  it  is  desired  to  keep  a  given  food.  Fruits 
and  vegetables  must  not  be  subjected  to  a  freezing  temper- 
ature, while  meats,  fish,  and  poultry  can  be  preserved  longer 
if  frozen  solid;  they  must  be  thawed  slowly,  otherwise 
the  meat  becomes  flabby.  It  is  customary,  when  putting 
fish  in  cold  storage,  to  freeze  them  solid  and  then  dip  the 
fish  into  cold  water,  so  that  a  case  of  ice  forms  around 
the  fish  and  remains  while  it  is  in  cold  storage,  effectu- 
ally excluding  all  contamination.    Investigators  differ  with 


PRESERVATION  OF  FOODS  131 

reference  to  the  length  of  time  meats  and  other  foods  may 
be  kept  in  cold  storage  without  deterioration.  Some  have 
concluded  that  after  three  months  meats  begin  to  lose  in 
flavor  and  nutritive  value,  while  other  investigators  have 
concluded  that  if  a  sufficiently  low  temperature  is  employed, 
meats  may  be  kept  in  good  condition  for  years.  As  a  matter 
of  practice,  eggs,  poultry,  fish,  and  game  are  kept  from  one 
season  to  the  next ;  that  is,  on  the  average  eight  or  nine 
months.  For  financial  reasons  no  large  amount  of  these 
foods  can  be  held  any  longer.  While  the  flavor  of  cold- 
storage  food  is  somewhat  impaired,  its  nutritive  value  is 
unaffected  if  it  has  been  properly  stored. 

Sterilization.  High  temperatures  kill  bacteria,  while  low 
temperatures  merely  retard  or  prevent  their  growth,  unless 
continued  for  a  long  time.  As  has  been  explained  in  the 
chapter  on  bacteria,  these  organisms  differ  in  their  power 
to  resist  high  temperatures.  A  very  large  proportion  are 
destroyed  at  a  comparatively  low  temperature.  This  fact 
is  taken  advantage  of  in  the  Pasteurization  of  milk.  Such 
milk  will  remain  sweet  for  several  days.  By  subjecting  the 
milk  or  other  food  product  to  a  temperature  somewhat 
above  the  boiling  point  of  water,  all  bacteria  and  their 
spores  are  killed.  This  fact  is  utilized  in  the  canning  of 
fruits,  meats,  etc.  If  the  containers  of  such  food  are  prop- 
erly sealed,  so  that  no  bacteria  can  gain  entrance,  the  food 
will  remain  unchanged  for  an  indefinite  time.  This  method 
of  preservation  is  ideal  for  food  which  requires  cooking 
before  being  eaten,  and  is  therefore  employed  very  largely 
with  fruits,  vegetables,  fish,  meats,  etc.  There  is  some 
danger  that  poisons  may  be  introduced  into  the  food  from 
the  container.  The  acids  of  fruits,  for  instance,  will  quite 
easily  dissolve  any  lead  which  may  be  present  in  the  solder, 
while  the  tin  of  the  cans  largely  used  as  containers  is 


132  PURE  FOODS 

acted  upon  more  slowly.  The  tin  must  be  pure  and  the 
soldering  done  in  such  a  manner  that  none  of  this  material 
comes  in  contact  with  the  contents  of  the  can.  Glass  and 
porcelain  are  the  best  materials  for  the  containers. 

Preservation  by  smoking.  The  fourth  method  of  preserva- 
tion of  foods  by  means  of  preservatives  has  been  used  from 
very  early  times.  The  use  of  smoke  for  the  preservation  of 
meat  and  fish  was  probably  discovered  while  men  lived  as 
savages.  It  is  a  very  effective  method,  because  smoke  con- 
tains a  very  powerful  antiseptic  known  as  creosote.  This 
and  a  number  of  other  substances  contained  in  smoke  are 
highly  poisonous,  but  the  amount  of  these  substances  which 
is  present  in  preserved  foods  is  so  small  that  no  ill  results 
follow  the  use  of  such  foods  unless  they  are  consumed  con- 
tinuously to  the  exclusion  of  other  foods.  A  quick  process 
for  producing  effects  similar  to  smoking  consists  in  dipping 
the  meat  in  pyroligneous  acid.  This  liquid  is  obtained  by 
the  dry  distillation  of  wood  and  may  be  considered  con- 
densed smoke.  Meats  cured  in  this  manner  are  not  of  as 
fine  a  flavor  as  when  smoked. 

Common  salt.  This  has  only  slight  preservative  powers. 
It  hinders  the  growth  of  bacteria  only  when  present  in  fairly 
large  amount,  so  as  to  form  a  fairly  strong  solution  with 
any  liquid  present.  It  must  also  be  considered  a  food,  as  it 
is  an  essential  constituent  of  the  serum  of  the  blood.  It  is 
largely  used  as  a  seasoning  or  condiment,  especially  with 
vegetables.  It  is  generally  eaten  in  very  much  larger  quan- 
tities than  necessary  to  supply  the  needs  of  the  system.  The 
excess  is  eliminated  largely  through  the  kidneys,  requiring 
considerable  labor  by  these  frequently  overworked  organs. 

Vinegar  and  alcohol.  These  also  have  only  slight  preserva- 
tive powers,  being  efficient  only  when  the  acetic  acid  of  the 
vinegar  or  the  alcohol  forms  a  fairly  concentrated  solution. 


PRESERVATION  OF  FOODS  133 

Both  of  these  substances  are  foods  because  they  are  oxidized 
in  the  system  with  the  liberation  of  energy.  As  neither  of 
them  can  be  consumed  in  more  than  very  moderate  quanti- 
ties, without  serious  injury,  they  cannot  be  used  to  any 
great  extent  for  the  preservation  of  foods. 

Spices  are  added  to  foods  mainly  to  improve  the  flavor. 
They  assist  very  materially  in  digestion  by  stimulating  the 
flow  of  the  digestive  fluids.  Most  of  the  spices  have  also 
marked  preservative  powers.  Very  few  foods,  however,  can 
be  spiced  sufficiently  to  preserve  them. 

Sugar  in  concentrated  solution  almost  entirely  prevents 
the  growth  of  bacteria,  while  in  dilute  solutions  they  flourish 
and  grow  rapidly.  For  this  reason  jams  and  jellies  do  not 
readily  spoil,  while  candies  will  keep  almost  indefinitely. 
As  has  already  been  shown,  sugar  is  a  highly  concentrated 
food,  so  that  the  calorific  value  of  food  preserved  in  this 
manner  is  greatly  increased  and  the  essential  characteristics 
of  the  fruits  very  much  changed. 

Efficiency  of  chemical  preservatives.  The  modern  chemical 
preservatives  are  substances  which  have  very  high  preserva- 
tive powers  and  no  food  or  condimental  properties  what- 
ever. They  have  but  one  function  in  foods,  except  in  one 
or  two  cases  where  they  also  serve  to  increase  the  natural 
color  somewhat.  Their  very  marked  preservative  power  is 
evident  from  the  fact  that  they  are  generally  added  to  foods 
in  proportions  of  from  1-50,000  to  1-1000.  In  even  the 
smaller  of  these  proportions  the  effect  is  very  marked. 

Chemical  preservatives  tasteless.  The  most  important 
question  in  regard  to  these  preservatives  is  whether  they  are 
themselves  injurious  to  health,  and  whether  foods  to  which 
they  have  been  added  are  wholesome.  This  question  is  not 
raised  in  regard  to  the  long-used  preservatives,  salt,  vinegar, 
smoke,  etc.,  although  some  of  these  contain  substances  which 


134  PURE  FOODS 

in  concentrated  form  are  violent  poisons.  The  taste  of  these 
substances  is  so  pronounced  that  their  presence  in  foods  is 
instantly  detected,  and  their  properties  are  so  well  known 
that  there  is  no  necessity  of  protecting  the  public  by  legal 
enactments.  The  chemical  preservatives,  on  the  other  hand, 
give  no  evidence  whatever  by  the  sense  of  taste  of  their  pres- 
ence. Having  been  used  in  foods  for  a  comparatively  short 
time,  their  effect  on  the  human  system  is  not  thoroughly 
understood,  while  the  claim  has  often  been  made  that  they 
are  poisonous  and  that  their  use  should  be  prohibited. 

The  dose  of  poisons.  In  attempting  to  decide  this  question 
by  experiments  on  animals  and  human  beings,  the  fact  is 
frequently  overlooked  that  the  quantity  of  a  substance  con- 
sumed has  an  important  bearing  on  its  effect  on  the  animal 
organism.  Minute  doses  of  the  most  violent  poisons  may 
be  taken  with  little  or  no  effect.  As  the  size  of  the  dose  is 
increased,  the  effects  become  more  marked  until  the  fatal 
dose  is  reached.  Large  doses  are  apt  to  be  rejected  and 
therefore  not  prove  fatal.  The  size  of  the  injurious  or  fatal 
dose  differs  not  only  with  the  poison  but  also  with  the  indi- 
vidual. This  personal  peculiarity  is  called  idiosyncrasy. 
In  the  case  of  animals  this  is  strikingly  illustrated  by  the 
fact  that  chickens  can  stand  ten  times  and  guinea  pigs 
three  times  as  much  strychnine  as  is  fatal  to  rabbits,  while 
dogs  can  be  given  enough  corrosive  sublimate  to  sterilize 
the  entire  digestive  tract  without  fatal  results. 

Cumulative  poisons.  While  a  smgle  minute  dose  of  most 
poisons  can  be  taken  without  any  noticeable  effect,  the 
repeated  consumption  of  small  doses  of  the  same  poisons 
leads  to  serious  or  even  fatal  results  for  two  reasons :  If  the 
poison  is  cumulative,  it  will  remain  in  the  system,  so  that 
numerous  small  doses  may  ultimately  produce  very  much 
the  same  effect  as  a  single  large  dose  of  the  poison.    Minute 


PEESERVATIOK  OF  EOODS  135 

doses  of  other  poisons  produce  a  slight  injury  to  one  or 
more  organs  of  the  body.  Repeated  doses  increase  the  in- 
jury, until  finally  the  organ  affected  breaks  down  utterly, 
and  serious  illness  or  death  results  in  spite  of  the  mar- 
velous recuperative  power  of  the  human  system. 

Poisons  commonly  consumed.  Human  beings  have  from 
time  immemorial  consumed  substances  which  must  be  classed 
as  poisons.  Among  these  are  such  well-known  substances 
as  alcohol  and  nicotine  (the  poisonous  principle  of  tobacco). 
While  the  consumption  of  these  substances  in  large  quanti- 
ties is  undoubtedly  injurious  and  may  even  be  fatal,  it  has 
been  by  no  means  demonstrated  that  they  are  injurious  when 
consumed  in  small  quantities.  It  is  well  known  that  adults 
are  far  less  injuriously  affected  by  these  poisons  than  is  the 
case  with  the  immature.  Acetic  acid,  the  active  principle 
of  vinegar,  is  a  poison  in  concentrated  form.  Muriatic  or 
hydrochloric  acid  is  a  poison,  and  yet  it  is  always  present 
in  the  stomach  and  aids  digestion.  Enough  of  this  acid  is 
produced  and  poured  into  the  stomach  during  twenty-four 
hours  to  constitute  a  fatal  dose  if  the  total  quantity  were 
present  at  a  given  moment. 

Chemical  preservatives  are  drugs.  In  studying  the  sub- 
stances which  are  used  as  preservatives  in  foods,  it  is  found 
that  all  of  them  may  be  classed  as  drugs ;  that  is,  they  have 
a  specific  effect  on  some  function  or  organ  of  the  human 
system,  so  that  they  are  used  as  medicines.  The  medicinal 
dose  of  these  substances  varies  from  5  to  40  grains,  or  from  l 
to  21-  gm.  With  some  foods  enough  would  not  ordinarily  be 
consumed  to  give  this  amount,  but  in  other  cases  a  sufficient 
amount  would  be  taken  to  produce  physiological  effects. 
While  a  healthy  person  might  not  suffer  from  such  promis- 
cuous use  of  medicines,  serious  results  might  be  produced 
with  the  sick  or  weak. 


136  PURE  FOODS 

Digestion  experiments  have  been  carried  out  in  the  labora. 
tory  with  food  treated  with  preservatives  and  subjected  to 
the  action  of  the  digestive  ferments,  such  as  pepsin,  rennin, 
amylopsin  (pancreatic  ferment),  and  trypsin.  The  time 
required  for  the  digestion  is  generally  very  much  increased, 
although  in  some  cases  the  digestion  seem$  to  be  accelerated. 
Experiments  have  been  carried  out  on  animals.  Dogs,  pigs, 
and  rabbits  showed  no  ill  effects  when  fed  on  food  contain- 
ing borax  or  boric  acid.  Young  kittens  died  when  fed  on 
milk  containing  borax,  while  kittens  older  than  three  months 
were  not  affected.  In  some  instances  where  the  animal 
seemed  to  be  entirely  healthy,  it  was  killed  and  its  vital 
organs  examined.  In  many  cases  the  kidneys  showed  signs 
of  degeneration,  due  undoubtedly  to  the  fact  that  most 
preservatives  must  be  eliminated  through  these  organs.  It 
is  somewhat  alarming  to  learn  that,  while  apparently  in 
good  health,  a  vital  organ  can  slowly  become  diseased  from 
the  food  eaten. 

Experiments  on  human  beings.  Very  extensive  experi- 
ments have  been  carried  out  on  human  beings.  While  a 
few  of  these  have  been  conducted  on  children  or  invalids, 
most  of  them  have  been  carried  out  on  healthy  young  men. 
In  some  of  these  experiments  no  ill  effects  have  been  noted, 
while  in  others,  loss  of  appetite  and  weight,  headache,  and 
nausea  have  been  observed.  The  most  careful  and  exten- 
sive investigations  of  this  kind  are  being  carried  out  by  the 
Referee  Board  of  the  United  States  Department  of  Agri- 
culture. Three  separate  squads  of  young  men  have  been 
experimented  upon  by  being  fed  with  food  containing  ben- 
zoate  of  soda.  No  evidence  of  disturbance  of  the  digestion 
was  discovered.  The  assimilation  of  the  food,  as  well  as  the 
elimination  of  waste  products,  was  entirely  normal.  The 
board  concluded  that  4  gm.  of  benzoate  of  soda  per  day 


PEESEKVATION  OF  FOODS  137 

could  be  consumed  with  the  food  without  harm.  No  experi- 
ments on  children  were  conducted  by  the  board.  In  view 
of  the  results  of  previous  experiments,  it  is  quite  possible 
that  the  immature  or  aged  may  suffer  from  the  consumption 
of  a  preservative,  while  vigorous  young  men  might  be  un- 
affected. Even  though  the  preservative  itself  is  entirely 
harmless,  foods  prepared  with  it  may  be  unwholesome  and 
inferior  to  foods  prepared  without  it,  so  that  it  might  be 
desirable  to  prohibit  its  use. 

The  action  of  preservatives  toward  bacteria  is  of  interest 
and  importance.  Among  the  large  number  of  bacteria  which 
gain  entrance  into  foods,  only  a  few  give  rise  to  the  disagree- 
able taste  and  odors  which  we  associate  with  decomposing 
foods.  Substances  have  been  selected  as  food  preservatives 
on  account  of  their  ability  to  preserve  the  natural  taste  and 
odor  of  foods,  and  not  for  their  ability  to  prevent  the  growth 
of  bacteria  in  general.  Direct  experiments  upon  this  point 
have  shown  that  the  action  of  preservatives  on  bacteria  is 
selective ;  that  is,  the  growth  of  some  species  is  retarded  far 
more  than  that  of  other  species.  The  bacteriological  exami- 
nation of  preserved  and  unpreserved  foods  has  shown  that 
when  a  disagreeable  odor  and  taste  begin  to  appear,  the 
preserved  contain  a  much  larger  number  of  bacteria  than 
the  unpreserved.  In  other  words,  the  preservatives  prevent 
the  growth  of  bacteria  which  produce  the  foul  odors  and 
taste,  and  allow  other  bacteria  to  grow  at  a  rapid  rate.  In 
round  numbers,  the  preserved  foods  can  contain  about  four 
times  as  many  bacteria  as  the  unpreserved  before  seeming 
to  be  spoiled. 

Danger  of  consuming  large  numbers  of  bacteria.  A  con- 
siderable amount  of  evidence  has  been  produced  to  show 
that  even  in  the  absence  of  any  specific  disease  germs,  the 
consumption  of  foods  containing  a  large  number  of  bacteria 


138  PUEE  FOODS 

increases  the  death  rate.  This  has  been  repeatedly  shown 
with  pubhc  water  suppUes.  If  the  bacteria  content  is  re- 
duced by  filtration  or  other  means,  not  only  is  there  a  reduc- 
tion in  the  death  rate,  due  to  typhoid  and  other  diseases 
known  to  be  caused  by  water-borne  bacteria,  but  the  death 
rate  due  to  other  diseases  is  also  materially  reduced.  The 
same  result  has  been  repeatedly  observed  with  milk.  The 
death  rate  among  children  is  reduced  when  milk  containing 
a  smaller  number  of  bacteria  is  used.  It  would  appear, 
therefore,  that  the  use  of  preserved  food  is  a  menace  to 
public  health  because  such  foods  may  be  consumed  while 
swarming  with  bacteria. 

Preservation  of  decomposed  foods.  Another  very  impor- 
tant question  is  whether  the  use  of  preservatives  renders 
it  possible  for  manufacturers  to  use  inferior  or  decomposed 
foods.  Formaldehyde  has  been  used  to  a  considerable  ex- 
tent to  deodorize  eggs  which  were  too  badly  decomposed 
to  be  sold.  For  this  purpose  the  eggs  are  broken,  the  shells 
removed,  and  the  liquid  treated  with  formaldehyde.  This 
practice  has  been  very  largely  stopped  by  the  health  officers. 
Sulphites  have  been  very  largely  used  in  the  preparation  of 
sausage  meat  or  Hamburg  steak  from  the  trimmings  and 
odd  ends  which  accumulate  in  the  meat  shops.  These  scraps 
must  not  be  allowed  to  become  too  much  tainted  or  the  sul- 
phite will  not  remove  the  odor.  It  is  very  effective,  how- 
ever, in  restoring  the  bright  red  color  to  meat  which  has 
become  dark.  On  chopping  such  meat  and  adding  the 
sulphite  a  very  attractive  sausage  meat  can  be  produced. 
Especially  when  it  is  exposed  to  the  air  the  meat  acquires 
a  bright  red  color. 

Preservatives  vs.  cleanliness.  Taking  human  nature  as 
it  is,  it  would  seem  that  the  use  of  preservatives  would 
not  lead  to  the  adoption  of  the  most  sanitary  methods  of 


PRESERVATION  OF  FOODS  139 

handling  foods.  Foods  could  be  kept  by  the  aid  of  pre- 
servatives quite  as  long,  even  though  strict  cleanliness  were 
not  observed.  When  we  remember  that  bacteria  will  grow 
most  luxuriously  in  the  presence  of  preservatives,  the  foods 
handled  in  this  way  cannot  but  be  dangerous  to  health.  One 
of  the  strongest  reasons  why  the  catsup  manufacturers  de- 
sire to  use  preservatives  is  that  they  have  been  accustomed 
to  handle  and  keep  tomato  pulp  in  bulk  until  it  is  con- 
venient to  work  it  up  into  catsup.  The  finished  product  is 
also  sold  in  barrels  to  restaurants,  where  it  is  put  in  con- 
venient receptacles  for  the  table  until  the  stock  is  exhausted. 
There  is  no  question  but  that  the  liability  to  contamination 
of  the  catsup  under  these  conditions  is  very  great.  A  very 
thorough  overhauling  of  the  process  would  be  necessary  if 
the  use  of  preservatives  were  prohibited.  While  benzoate  of 
soda  has  been  found  to  be  harmless  in  the  amounts  used  in 
foods  when  consumed  by  healthy  adults,  the  evidence  at 
hand  with  reference  to  the  other  chemical  preservatives 
would  lead  to  the  conclusion  that  the  consumption  of  foods 
containing  them  is  attended  with  more  danger,  especially 
since  the  most  sanitary  methods  may  not  have  been  used 
in  the  preparation  of  the  food.  It  is  of  the  greatest  impor- 
tance that  the  statement  be  made  on  the  label  of  foods  that 
they  contain  a  given  preservative,  in  order  that  consumers 
may  avoid  such  foods  particularly  when  in  poor  health  from 
organic  diseases,  especially  of  the  kidneys. 

Hydrogen  peroxide.  These  general  statements  about  pre- 
servatives do  not  apply  to  hydrogen  peroxide.  This  com- 
pound decomposes  very  quickly  when  added  to  foods.  The 
decomposition  products  are  oxygen  and  water.  The  oxygen 
serves  to  destroy  the  bacteria  present. 

Preservatives  do  not  sterilize  foods.  The  statement  has  fre- 
quently been  made  that  the  consumption  of  foods  containing 


140  PURE  FOODS 

preservatives  is  accompanied  with  less  risk  because  the  pre- 
servative will  kill  bacteria  which  are  present.  This  state- 
ment is  by  no  means  correct,  as  preservatives  are  never 
added  in  sufficient  amount  to  sterilize  foods.  In  the  amount 
used  they  simply  retard  the  growth  of  the  bacteria,  espe- 
cially those  which  produce  the  disagreeable  odor  and  taste 
in  decomposed  foods.  So  that  there  can  be  present  in  foods 
containing  preservatives  a  very  much  greater  number  of 
bacteria,  before  they  emit  any  disagreeable  odor  or  taste, 
than  is  possible  with  foods  containing  no  preservatives. 
Sterilization  Avith  heat,  on  the  other  hand,  absolutely  de- 
stroys bacteria  which  may  be  present,  and  is  therefore  a 
much  safer  method  of  preservation  of  foods. 


CHAPTER   XIII 

FRUITS,   JAMS,   AND  JELLIES 

Composition  of  fruits.  Fruits  are  composed  very  largely 
of  water,  containing  on  the  average  80  to  90  per  cent.  Most 
of  the  other  constituents  are  held  in  solution  by  this  water. 
The  solids  are  composed  of  sugars,  gums,  organic  acids, 
starch,  a  small  amount  of  cellulose,  mineral  matter,  and 
aromatic  substances  such  as  essential  oils  and  compound 
ethers.  A  small  amount  of  coloring  matter  is  also  present. 
Chlorophyll  gives  the  green  color,  xanthophyll  the  yellow 
color,  and  erythrophyll  the  red.  The  other  shades  are  pro- 
duced by  a  combination  of  these  fundamental  colors  in  vary- 
ing proportions.  With  the  exception  of  the  mineral  matter, 
all  of  these  substances  are  carbohydrates ;  that  is,  they  are 
composed  of  carbon,  hydrogen,  and  oxygen.  The  carbon  is 
obtained  from  the  carbon  dioxide  of  the  air,  which  is  decom- 
posed by  the  plant  with  the  aid  of  sunlight,  giving  off  free 
oxygen.  The  oxygen  and  hydrogen  are  obtained  mainly 
from  water.  The  mineral  constituents  are  obtained  from 
the  soil,  being  carried  to  the  plant  in  solution  in  water. 

Changes  in  composition  during  ripening.  Fruits  in  the 
green  state  contain  a  large  amount  of  starch,  which  is  con- 
verted into  sugar  as  the  fruit  ripens.  The  amount  of  sugar 
in  some  ripe  fruits  is  very  large.  Grapes  may  contain  as 
much  as  25  to  30  per  cent,  apples  5  to  15  per  cent,  and 
such  sweet  fruits  as  peaches  and  pears  almost  as  much  as 
this.  This  is  another  instance  in  which  plants  exhibit  the 
ability  to  change  the  insoluble  carbohydrate,  starch,  into 

141 


142 


PURE  FOODS 


sugar.  Starch  is  a  very  convenient  and  stable  form  in 
which  the  plant  can  store  nourishment  for  future  use. 
When  fruits  decay  or  their  juices  are  allowed  to  ferment, 
the  sugar  undergoes  another  transformation  by  which  al- 
cohol is  produced.  In  this  manner  cider  and  wine  are 
made.  The  following  table  shows  the  transformations  which 
take  place  during  the  growth  and  ripening  of  apples. 


TABLE  XXIII 
Composition  of  Apples  at  Various  Stages  of  Growth 


Very  green 

Green 

Ripe 

Overripe 

Average  for 
American  apples 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Total  solids   .    . 

18.47 

20.19 

19.64 

19.74 

Cane  sugar    .    . 

1.63 

4.05 

6.81 

5.26 

3.40 

Invert  sugar  .    . 

6.40 

6.46 

7.70 

8.81 

7.90 

Starch    .... 

4.14 

3.67 

0.17 

Malic  acid     .    . 

1.14 

0.65 

0.48 

This  table  shows  very  clearly  how  the  large  amount  of 
starch  in  green  apples  gradually  becomes  converted  mto 
sugar.  Taken  in  connection  with  the  disappearance  of  a 
large  portion  of  the  malic  acid,  the  great  difference  in  taste 
between  the  green  and  the  ripe  apple  is  accounted  for.  A 
similar  transformation  takes  place  in  the  apples  which  are 
stored  for  consumption  during  the  winter.  In  the  fall  the 
apple  is  hard  and  tasteless  because  it  contains  a  large 
amount  of  starch.  In  the  spring  it  is  mellow  and  sweet 
because  the  starch  has  been  converted  into  sugar.  The 
green  apple  is  indigestible  because  of  its  large  content  of 
starch,  which  cannot  be  digested  in  the  raw  state.  No  ill 
results  follow  if  such  apples  are  cooked  before  they  are 
eaten,  although  they  still  contain  a  large  amount  of  acid. 


FRUITS,  JAMS,  AND  JELLIES  143 

The  acids  found  in  fruits  are  quite  similar  to  each  other. 
They  are  all  organic  acids,  being  composed  of  carbon, 
hydrogen,  and  oxygen.  They  can  therefore  be  oxidized  in 
the  human  system  so  as  to  liberate  their  energy.  Most  of 
these  acids  are  white  solids.  Besides  malic  acid,  which  is 
found  in  apples,  citric  acid  found  in  lemons  and  oranges, 
and  tartaric  acid  found  in  grapes,  are  typical  of  this  class 
of  substances.  Citric  and  tartaric  acids  are  separated  in 
large  quantities  for  various  purposes. 

Cream  of  tartar.  Tartaric  acid  is  present  in  grapes  in 
the  form  of  the  acid  salt  of  potassium,  which  is  known  as 
cream  of  tartar.  It  is  obtained  in  large  quantities  in  the 
process  of  making  wine.  When  the  juice  is  pressed  out  of 
the  grapes,  most  of  the  cream  of  tartar  is  present  in  the 
expressed  juice,  while  a  small  portion  remains  in  the  solid 
portion  of  the  grape,  known  as  pomace.  When  the  grape 
juice  is  fermented  and  the  sugar  converted  into  alcohol, 
the  cream  of  tartar  crystallizes  out  because  it  is  insoluble 
in  alcohol.  It  settles  out  on  the  bottom  of  the  wine  casks 
and  is  known  in  this  crude  state  as  argols  or  lees.  Large 
quantities  of  this  product  are  imported  from  Italy  and 
France  and  refined  in  the  United  States.  The  cream  of 
tartar  is  first  dissolved  in  water,  the  solution  filtered  and 
allowed  to  crystallize.  The  brown  crystals  are  again  dis- 
solved, the  impurities  precipitated  and  filtered  out,  and  the 
solution  clarified  by  filtration  through  bone  black,  after 
which  pure  white  crystals  are  obtained.  These  are  pow- 
dered and  used  in  making  baking  powder  and  also  sold 
as  cream  of  tartar. 

Tartaric  acid.  If  tartaric  acid  is  desired,  the  potassium 
must  be  removed  from  the  cream  of  tartar.  This  is  done 
by  the  addition  of  sulphuric  or  phosphoric  acids,  which 
combuae  with  the  potassium,  after  which  the  tartaric  acid 


144  PUEE  FOODS 

may  be  crystallized  out.  It  is  purified  by  recrystallization 
in  the  same  manner  as  the  cream  of  tartar.  Both  of  these 
compounds  are  used  in  the  manufacture  of  baking  powder. 
Cream  of  tartar  has  acid  properties  because  it  contains  only 
half  the  amount  of  potassium  necessary  to  neutralize  the 
tartaric  acid. 

Citric  acid.  This  acid  is  prepared  from  the  juice  of  lemons, 
the  rinds  being  pressed  for  their  essential  oil.  By  far  the 
greatest  quantity  is  produced  in  Sicily,  and  smaller  quanti- 
ties in  other  localities  where  the  fruit  grows  abundantly. 

Mineral  matter.  Fruits  contain  a  fairly  large  amount  of 
mineral  matter,  as  has  already  been  shown.  Grapes  contain 
a  considerable  amount  of  potassium  in  combination  with 
tartaric  acid.  Calcium,  iron,  aluminium,  phosphorus,  and 
manganese  are  also  present  in  small  amounts.  These  mm- 
eral  constituents  of  fruits  are  in  excellent  condition  for 
digestion  and  absorption  by  the  system.  They  cannot  he 
absorbed  when  taken  in  pure  form,  but  must  first  be  com- 
bined with  organic  matter.  This  the  plant  does  in  produc- 
ing the  fruit.  Inorganic  salts  of  the  metals  are  assimilated 
only  to  a  slight  extent. 

Flavor  of  fruits.  The  characteristic  flavor  of  fruits  is 
produced  by  very  small  quantities  of  compounds  known  as 
compound  ethers  or  ethereal  salts.  One  of  the  simplest  of 
these  is  ethyl  acetate.  It  may  be  easily  produced  from 
acetic  acid  and  ordinary  alcohol,  which  is  called  by  chem- 
ists ethyl  alcohol.  By  warming  these  two  substances  with 
concentrated  sulphuric  acid  they  combine  to  form  ethyl 
acetate,  which  may  be  purified  by  distillation.  It  is  a  color- 
less mobile  liquid  of  a  pleasant  fruity  odor.  Amyl  acetate 
may  be  produced  in  a  similar  manner  from  amyl  alcohol 
and  acetic  acid.  It  is  known  as  banana  oil.  Its  odor  is 
very  similar  to  that  of  ripe  bananas.   Amyl  valerianate  is  a 


FRUITS,  JAMS,  AND  JELLIES 


145 


compound  of  amyl  alcohol  and  valerianic  acid,  and  has  an 
odor  very  similar  to  that  of  apples.  The  odor  of  few  if  any 
fruits  is  produced  by  a  single  substance,  but  is  generally 
due  to  the  presence  of  several  ethers.  Artificial  fruit  flavors 
are  made  by  combining  several  of  these  compounds,  and 
often  resemble  in  odor  very  closely  the  natural  fruits. 

Pectin.  Another  constituent  of  fruits,  which  causes  the 
juices  to  solidify  into  jelly  when  boiled  with  sugar,  is  known 
as  pectin  or  pectose.  It  is  a  carbohydrate  and  produces  a 
jelly  only  in  the  presence  of  a  definite  amount  of  acid,  five 
tenths  per  cent  seeming  to  be  the  amount  most  favorable 
to  the  formation  of  a  good  jelly.  ^ 

The  following  table  gives  the  composition  of  a  number 
of  our  common  fresh  fruits : 


TABLE  XXIV 
Composition  of  Fresh  Fruits 


Fruit 

Water 

Total 
sugar 

Protein 

Acid 

Ash 

Calories 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Apples    .... 

85.4 

11.27 

0.64 

0.70 

0.27 

290 

Bananas     .    .    . 

73.8 

21.7 

1.17 

0.30 

0.5 

460 

Blackberries  .    . 

86.3 

10.9 

1.3 

0.77 

0.5 

Cranberries    .    . 

88.9 

9.9 

0.4 

2.34 

0.2 

215 

Grapes    .... 

80.12 

16.50 

1.26 

0.59 

0.5 

450 

Huckleberries     . 

81.9 

16.50 

0.6 

0.3 

345 

Lemons  .... 

88.0 

0.37 

5.39 

205 

Oranges      .    .    . 

86.0 

5.65 

1.35 

240 

Peaches      .    .    . 

88.0 

10.8 

0.7 

0.56 

0.7 

190 

Pineapples      .    . 

85.19 

12.22 

0.48 

0.77 

0.42 

Plums     ,    .    .    . 

78.4 

13.25 

0.4 

1.00 

0.52 

395 

Strawberries 

90.0 

7.00 

0.9 

1.10 

0.6 

180 

Raspberries    .    . 

84.0 

12.6 

1.7 

1.48 

0.6 

310 

1  N.  E.  Goldthwaite,  Jour,  of  Ind.  andEng.  Chem.,  Vol.  I,  p.  333. 


146  PUEE  FOODS 

The  delicious  flavor  of  most  fruits  is  due  to  the  combi- 
nation of  the  sweet  taste  of  the  sugars  dissolved  in  the 
water  of  the  fruit,  to  which  the  acid  gives  an  agreeable 
contrast,  and  the  essential  oils  and  ethers  which  give  the 
characteristic  fruit  flavor  and  aroma.  The  natural  varia- 
tions in  the  amount  of  sugar  and  acid,  as  well  as  essential 
oils  and  ethers  present  in  different  fruits,  are  sufficient  to 
suit  all  tastes  and  personal  idiosyncrasies. 

Food  values  of  fruits.  It  will  be  observed  that  bananas 
have  the  greatest  food  value  among  fruits  on  account  of 
the  large  percentage  of  sugar.  Grapes  are  very  nearly 
as  rich  in  this  constituent.  While  the  percentage  of  pro- 
tein is  apparently  small,  it  is  quite  appreciable  in  propor- 
tion to  the  total  solids,  of  which  the  protein  constitutes 
from  2  to  10  per  cent.  The  fruit  acids  constitute  a  still 
larger  proportion  of  the  total  solids ;  that  is,  from  1  to 
45  per  cent. 

Fresh  fruits  constitute  good  summer  diet.  On  account  of 
the  small  calorific  value,  a  diet  of  fruits  would  not  be  very 
nourishing  unless  a  very  large  amount  were  consumed. 
For  this  reason  they  are  admirably  adapted  to  be  the  food 
of  people  living  in  tropical  countries,  and  as  a  summer 
diet  when  a  high  calorific  value  is  unnecessary.  The  acid 
present  in  fruit  is  also  desirable  during  the  summer, 
although  in  some  cases  it  acts  injuriously.  In  eating  raw 
fruits  there  is  some  danger  from  bacteria  adhering  to  the 
surface,  especially  when  the  fruit  has  been  exposed  for 
sale  on  a  dusty  street. 

Preserved  fruits  constitute  good  winter  diet.  While  fresh 
fruits  form  a  most  desirable  food  for  the  summer,  preserved 
fruits,  especially  jams  and  jellies,  are  well  adapted  for  con- 
sumption during  the  winter,  on  account  of  the  high  calo- 
rific value  produced  by  the  large  amount  of  sugar  which 


FRUITS,  JAMS,  AKD  JELLIES  147 

has  been  added,  constituting  generally  at  least  50  per  cent 
of  the  preserved  fruit.  The  calorific  value  of  dried  fruits 
is  also  higher  than  that  of  fresh  fruits  because  most  of  the 
water  has  been  expelled. 

Cold  storage  of  fruits.  As  has  already  been  stated,  every 
method  of  preservation  must  kill  the  bacteria  present  or 
retard  their  growth  and  activity.  Cold  storage  is  well 
adapted  to  the  preservation  of  fruits,  provided  the  temper- 
ature is  not  allowed  to  fall  below  the  freezing  point. 
Many  fruits  may  be  kept  in  excellent  condition  by  this 
method  for  six  to  nine  months,  so  as  to  be  quite  as  palat- 
able as  the  fresh  fruits. 

Dried  fruits.  Preservation  of  fruits  by  drying  has  been 
practiced  for  centuries.  Until  recently  very  little  improve- 
ment has  been  made  over  the  primitive  method  of  drying 
in  the  sun.  The  modern  preservatives  have  been  used  to 
prevent  the  formation  of  mold  during  the  drying  process. 
Sulphurous  acid  has  been  most  largely  used,  because  the 
fruit  containing  it  does  not  darken  during  the  drying  proc- 
ess. The  fresh  fruit  is  exposed  to  the  fumes  of  burning 
sulphur  before  being  placed  on  the  drying  frames.  While 
some  of  the  sulphurous  acid  escapes  with  the  moisture,  a 
considerable  amount  always  remains  and  is  consumed  with 
the  fruit.  In  this  manner  the  so-called  evaporated  apples 
are  produced,  which  are  perfectly  white,  without  a  trace  of 
darkening. 

Desiccated  fruits.  The  necessity  of  using  preservatives 
is  entirely  obviated  when  a  method  of  drying,  recently  de- 
vised, is  employed.  Air  which  has  been  artificially  deprived 
of  its  moisture  and  then  heated  is  passed  over  the  fruit. 
The  moisture  is  taken  out  so  rapidly  that  molds  and  bac- 
teria cannot  grow.  The  dried  fruit  may  be  kept  indefinitely 
without  decomposition.     On    moistening  with   water  the 


148 


PURE  FOODS 


fruit  regains  its  flavor  and  bulk.    This  method  of  drying  is 
superior  in  many  ways  to  the  older  processes. 

Canned  fruits.  Preservation  by  means  of  heat  involves 
cooking  the  fruit.  In  some  cases  this  is  an  advantage 
because  the  fruit  is  made  more  digestible.  This  method 
cannot  be  used  with  some  fruits  because  the  flavor  is  de- 
stroyed by  cooking.  In  all  cases,  after  sterilization,  the 
entrance  of  bacteria  must  be  prevented.  This  is  generally 
accomplished  by  sealing  in  an  air-tight  container.  The  ex- 
clusion of  the  air  is  not  essential  to  the  preservation  of  the 
fruit.  It  would  keep  quite  as  well  if  placed  in  a  bottle 
closed  with  a  plug  of  cotton.  The  cotton  keeps  out  bac- 
teria, because  the  latter  are  found  on  particles  of  dust 
which  are  sifted  out  by  the  cotton. 

Jams  and  jellies.  Fruits  are  also  preserved  by  boiling 
with  sugar.  If  the  whole  fruit  is  used,  jam  is  produced. 
As  most  of  the  nutriment  of  fruits  is  in  solution  in  the 
juices,  the  composition  of  jams  and  jellies  is  very  similar. 
The  portion  discarded  in  making  jelly  is  quite  indigest- 
ible. The  following  table  gives  the  composition  of  jams 
and  jellies : 

TABLE  XXV 

Composition  of  Jams 


Fruit 

Solids 

Reducing 
sugar 

Cane 
sugar 

Total 
sugar 

Acid 

Protein 

Ash 

Per  cent 

Percent 

Percent 

Percent 

Percent 

Per  cent 

Percent 

Apple  .    .    . 

63.22 

25.52 

29.11 

54.63 

0.28 

0.18 

0.20 

Blackberry  . 

55.42 

18.77 

29.00 

47.77 

0.85 

0.74 

0.48 

Grape  .    .    . 

56.64 

33.44 

11.33 

44.77 

0.74 

0.53 

0.74 

Pear     .    .    . 

61.52 

13.20 

33.74 

46.94 

0.16 

0.31 

0.28 

Peach  .    .    . 

65.65 

36.48 

23.16 

59.64 

0.5 

Plum    .    .    . 

50.43 

28.29 

9.70 

38.00 

1.01 

0.53 

0.54 

Pineapple     . 

73.92 

14.05 

46.40 

60.45 

0.32 

0.31 

0.30 

FEUITS,  JAMS,  AND  JELLIES 


149 


TABLE  XXVI 
Composition  of  Jellies 


Fruit 

Total 
solids 

Reducing 
sugar 

Cane 
sugar 

Total 
sugar 

Acid 

Protein 

Ash 

Per  cent 

Per  cent 

Per  cent 

Percent 

Per  cent 

Per  cent 

Per  cent 

Apple  .    .    . 

59.18 

20.78 

33.04 

53.82 

0.28 

0.18 

0.22 

Blackberry  . 

59.63 

12.51 

44.90 

57.41 

0.48 

0.24 

0.33 

Crab  apple  . 

63.28 

34.93 

23.68 

58.61 

0.17 

0.14 

0.11 

Grape  .    .    . 

63.66 

32.29 

30.52 

62.81 

0.52 

0.18 

0.45 

Huckleberry 

63.02 

24.27 

32.74 

57.01 

0.25 

0.07 

0.28 

Orange     .    . 

68.56 

3.95 

62.52 

65.47 

0.17 

0.42 

'0.30 

Peach  .    .    . 

69.98 

8.75 

56.59 

65.34 

0.25 

0.18 

0.21 

Pear     .    .    . 

69.12 

6.58 

58.46 

65.04 

0.18 

0.16 

0.34 

Pineapple     . 

80.28 

22.13 

56.70 

78.83 

0.33 

0.39 

0.43 

Plum     .    .    . 

45.56 

19.18 

22.67 

41.85 

1.13 

0.35 

0.68 

Mixed  fruit  . 

66.58 

39.17 

24.22 

63.39 

0.37 

0.07. 

0.21 

Food  value  of  jams  and  jellies.  The  amount  of  sugar  in 
these  foods  is  about  50  per  cent.  Only  a  portion  of  it  is 
present  as  cane  sugar,  because  a  considerable  portion  of  the 
sugar  added  has  been  hydrolyzed  by  the  acid  of  the  fruit 
during  the  boiling.  A  portion  of  the  reducing  sugar  is  that 
naturally  present  in  the  ripe  fruit.  As  the  percentage  of 
total  solids  is  very  large,  these  foods  are  very  concentrated 
and  can  give  a  large  amount  of  energy.  The  fruit  flavor, 
acid,  and  color  make  them  very  palatable  foods. 

Jelly  making.  Jellies  are  characterized  by  a  peculiar 
consistency,  which  may  be  described  as  a  solid  of  very  slight 
strength.  While  the  jelly  retains  the  shape  of  the  mold  in 
which  it  is  cooled,  it  can  hardly  support  its  own  weight. 
The  constituents  of  fruits  which  cause  them  to  "  jell "  are 
pectin  and  acid.  Almost  all  fruits  contain  the  requisite 
amount  of  pectin,  but  many  of  the  sweet  fruits,  such  as 
peaches,  blackberries,  pears,   etc.,   contain  too  little  acid. 


150  PUKE  FOODS 

For  this  reason,  jelly  may  be  made  from  these  fruits  if  they 
are  used  before  they  are  fully  ripe.  The  fruit  juice  must 
contain  about  ^  per  cent  of  acid  and  1  per  cent  of  pectin. 
As  most  fruits  contain  a  sufficient  amount  of  pectin,  failure 
to  obtain  a  jelly  is  generally  due  to  the  absence  of  the 
requisite  amount  of  acid.  This  may  be  introduced  by  add- 
ing tartaric  acid,  or,  what  is  perhaps  more  satisfactory,  the 
juice  of  a  strongly  acid  fruit  may  be  mixed  with  that  of  a 
sweet  fruit.  The  fruit  juice  must  be  boiled  with  the  sugar 
long  enough  to  hydrolyze  a  portion  of  the  latter,  but  not 
long  enough  to  convert  all  of  the  cane  sugar  into  reduc- 
ing sugars.  The  proper  conditions  are  reached  when  the 
boiling  point  is  about  103°  C.  and  the  specific  gravity  of 
the  hot  mixture  is  1.28.1  The  proper  proportion  of  sugar 
is  also  important  and  varies  slightly  with  different  fruits. 
All  bacteria  are  killed  during  the  boiling  of  the  jelly. 
By  pouring  melted  paraffin  over  the  solidffied  jelly  the 
entrance  of  more  bacteria  is  effectually  prevented.  The 
growth  of  any  bacteria  which  may  gain  entrance  is  very 
slow  in  the  highly  concentrated  sugar  solution. 

Artificial  jellies.  It  has  been  assumed  in  the  preceding 
discussion  that  fruit  juice  and  sugar  are  the  only  constit- 
uents necessary  for  the  preparation  of  jams  and  jellies.  As 
made  in  the  household,  this  is  true.  The  food  market  has 
been  flooded  with  jams  and  jellies  which  have  been  manu- 
factured in  large  quantities  by  very  different  methods. 
Instead  of  the  various  fruit  juices,  apple  juice,  together 
with  an  artfficial  flavor  and  color,  has  been  substituted. 
The  apple  juice  would  give  the  necessary  pectin,  while  the 
added  color  and  flavoring  matter  would  suggest  the  fruit 
whose  jelly  was  imitated.  In  some  cases  the  fruit  flavor  is 
obtained  by  using  apple  juice  mixed  with  a  small  quantity 
1  N.  E.  Goldthwaite,  Jour,  of  Ind.  and  Eng.  (Jhem.,  Vol.  I,  p.  333. 


FRUITS,  JAMS,  AKB  JELLIES  151 

of  the  fruit  whose  flavor  is  desired.  A  cheaper  jelly  is 
obtained  by  using  gelatin  without  any  fruit  juice  at  all, 
even  that  of  the  apple  being  omitted.  The  slightly  acid  taste 
of  fruit  jellies  is  obtained  by  the  addition  of  organic  acids, 
such  as  tartaric  and  citric ;  although  at  times  mineral  acids, 
such  as  sulphuric  or  muriatic,  have  been  employed.  In  such 
artificial  jellies  glucose  has  been  largely  used  in  place  of 
sugar,  the  sweet  taste  being  given  by  saccharin.  Artificial 
coloring  and  flavoring  matter  complete  the  deception.  That 
the  consuming  public  can  be  easily  deceived  is  shown  by 
the  fact  that  large  quantities  of  such  artificial  jelly  has 
been  sold  under  a  variety  of  labels,  such  as  currant,  rasp- 
berry, strawberry,  etc.,  while  the  contents  of  the  jars  was 
identical  in  every  respect,  no  attempt  being  made  to  vary 
the  color  or  flavor. 

Wholesomeness  of  artificial  jellies.  These  artificial  jellies 
have  generally  contained  no  injurious  constituents  except 
the  mineral  acids  and  poisonous  coal-tar  dyes  or  artificial 
flavors.  The  apple  juice,  glucose,  and  gelatin  are  substances 
of  recognized  food  value.  The  fraud  practiced  on  the  public 
is  largely  one  of  deception.  The  protection  afforded  by 
pure-food  laws  has  been  the  exclusion  of  poisonous  con- 
stituents and  the  prohibition  of  the  use  of  deceptive  labels, 
making  it  illegal  to  sell  as  a  fruit  jelly  a  compound  of 
gelatin,  glucose,  aniline  dye,  and  artificial  flavoring  matter. 
If  the  ingredients  are  wholesome  foods,  a  label  stating  the 
contents  of  the  compound  is  a  sufficient  protection  to  the 
purchaser. 

Adulterated  jams.  In  a  similar  manner,  jams  are  con- 
sidered to  be  a  product  made  by  boiling  fruits  with  sugar. 
A  common  practice  with  dishonest  manufacturers  has  been 
to  make  jams  out  of  the  fruit  pulp  from  which  the  juice 
has  been  expressed  for  the  purpose  of  making  jelly.    By 


152  PUEE  FOODS 

cooking  with  sugar  or  glucose,  and,  if  necessary,  adding  an 
acid,  coloring  matter,  and  artificial  flavoring  matter,  a  prod- 
uct would  be  obtained  which  could  with  difficulty  be  dis- 
tinguished, without  a  chemical  analysis,  from  genuine  jam. 
Most  of  these  jams,  as  well  as  the  artificial  jellies,  would  be 
preserved  with  a  chemical  preservative  as  a  cheaper  method 
than  careful  sterilization  and  sealing  of  the  jars. 

EXPERIMENTS 

27.  Testing  fruits  for  starch.  Test  green  fruits,  such  as  apples, 
pears,  bananas,  etc.,  for  starch  by  applying  a  few  drops  of  iodine 
solution  to  the  freshly  cut  surface.  If  the  blue  color  does  not  develop, 
scrape  off  a  little  of  the  fruit  with  a  knife  and  treat  with  boiling 
water.  Allow  to  cool  and  repeat  the  test.  Repeat  the  test  with 
ripe  fruit. 

28.  Testing  fruits  for  pectin.  Prepare  samples  of  the  juices  of  both 
green  and  ripe  fruits  of  various  kinds,  such  as  apple,  peach,  currant, 
etc.  The  fruit  should  first  be  crushed,  then  warmed  and  strained 
through  cloth.  Place  5  ccm.  of  each  sample  in  a  test  tube,  add  an 
equal  volume  of  alcohol,  shake,  and  allow  to  stand.  The  gelatinous 
precipitate  which  settles  out  in  each  case  is  the  pectin  of  the  fruit. 
A  considerable  difference  in  amount  and  character  of  the  precipitate 
will  be  noticed. 

29.  Acidity  of  fruit  juices.  The  acidity  of  the  fruit  juices  prepared 
in  Experiment  28  is  determined  in  the  following  manner :  A  small 
portion  of  the  fruit  juice  is  diluted  with  ten  times  its  volume  of  dis- 
tilled water,  and,  while  stirring,  a  dilute  solution  of  caustic  soda  (see 
Experiment  14)  is  added  drop  by  drop  until  a  decided  change  of 
color  is  noted.  By  testing  with  red  and  blue  litmus  paper  it  will  be 
found  that  at  the  point  when  the  solution  changes  from  acid  to 
alkaline  a  decided  change  of  color  occurs.  The  litmus  paper  is  dyed 
with  a  vegetable  color,  which  is  red  in  acid  solution  and  blue  in 
alkaline  solution.  A  large  number  of  other  vegetables  contain  color- 
ing matter,  which  undergoes  a  decided  change  when  the  acid  present 
is  neutralized  with  a  base. 

Having  noted  the  change  in  color  at  the  point  where  all  the 
acid  is  neutralized,  measure  out  exactly  10  ccm.  of  the  fruit  juice, 


FRUITS,  JAMS,  AND  JELLIES  153 

dilute  with  100  ccm.  of  distilled  water,  and  titrate  with  fifth-normal 
or  tenth-normal  caustic  soda  solution  (see  Experiment  14)  until  the 
color  change  is  observed.  Calculate  the  per  cent  of  acid  present. 
For  this  purpose  1  ccm.  of  fifth-normal  caustic  soda  is  equal  to 
0.01  gm.  of  acid.  If  5  ccm.  of  soda  were  used  for  10  ccm.  of  the  juice, 

the  per  cent  of  acid  would  be  five  tenths  (- '— =  0.5  J. 

As  some  fruit  juices  contain  very  little  natural  color,  it  will  be 
necessary  to  use  litmus  or  some  other  indicator  to  ascertain  when 
enough  caustic  soda  solution  has  been  added.  Litmus  paper  may  be 
used  or  a  solution  of  the  dye,  or,  still  better,  a  solution  of  methyl 
orange.  This  indicator  is  prepared  by  dissolving  -^^  gm.  of  the  dye 
in  100  ccm.  of  water.  Only  a  few  drops  of  this  indicator  should 
be  added  to  the  solution  of  the  fruit  juices. 

When  the  acidity  of  the  fruit  juices  has  been  ascertained,  experi- 
ments may  be  carried  out  to  determine  the  jelly-making  properties 
of  the  juice.  The  nature  and  amount  of  the  pectin  present  will  also 
be  found  to  be  of  importance  for  this  purpose.  Equal  portions  of 
the  juice  and  sugar  are  boiled  and  set  aside  to  cool.  If  the  acidity 
of  the  juice  is  high,  a  portion  of  the  acid  may  be  neutralized  by  the 
addition  of  measured  volumes  of  the  caustic  soda  solution,  while  if 
the  juice  is  deficient  in  acid,  citric,  malic,  or  tartaric  acid,  or  some 
strongly  acid  fruit  juice,  may  be  added.  Experiments  may  also  be 
made  by  varying  the  proportions  of  sugar  and  juice. 

30.  Testing  for  fruit  juices.  The  colors  obtained  when  the  acid 
of  various  fruit  juices  is  neutralized  are  quite  different,  and  charac- 
teristic with  different  fruits.  A  considerable  amount  of  organic 
matter  is  also  present  in  fruit  juices,  which  is  precipitated  with  lead 
acetate  and  can  be  used  to  identify  natural  fruit  juices.  A  solution 
of  basic  lead  acetate  has  been  found  to  combine  the  alkalinity  with 
the  soluble  lead  necessary  to  give  both  of  these  reactions.  The 
solution  is  made  as  follows :  18  gm.  of  lead  acetate  are  dissolved 
in  70  ccm.  of  hot  distilled  water  and  11  gm.  of  lead  oxide  added. 
The  mixture  is  boiled  for  half  an  hour  with  occasional  stirring,  after 
which  it  is  allowed  to  settle  for  a  few  minutes  and  is  then  filtered. 
Enough  distilled  water  is  added  to  make  the  volume  about  81  ccm. 
The  solution  must  be  kept  in  well-stoppered  bottles.  A  dilute  solu- 
tion made  by  adding  about  four  volumes  of  water  to  one  volume  of 
the  strong  solution  will  be  found  suitable  for  the  following  tests : 


154  PURE  FOODS 

Place  equal  portions  of  the  fruit  juices  prepared  in  Experiment 
28  in  test  tubes  and  add  the  lead  subacetate  solution  until  no  further 
precipitate  or  change  in  color  is  produced.  Note  carefully  the  color 
changes  and  character  of  the  precipitates  obtained  from  these  pure 
fruit  juices. 

Test  commercial  samples  of  jams  and  jellies  as  follows :  Add 
equal  volumes  of  water,  warm,  and  stir  until  a  homogeneous  solution 
is  obtained,  and  filter.  Test  the  filtrates  with  the  lead  subacetate 
solution. 

31.  Testing  for  aniline  dyes.  As  most  artificial  jams,  jellies,  and 
other  fruit  products  are  colored  with  aniline  dyes  to  imitate  the 
natural  product,  the  test  for  the  dyes  gives  good  evidence  of  the 
character  of  the  products.  The  test  is  carried  out  as  follows  :  White 
woolen  cloth  is  cut  into  narrow  strips  and  freed  from  grease  by  boil- 
ing in  very  dilute  caustic  soda  solution  for  about  ten  minutes.  The 
soda  is  then  washed  out  by  boiling  in  water.  The  cloth  is  then  dried 
and  preserved  for  use. 

About  15  gm.  of  the  fruit  product  are  dissolved  in  100  ccm.  of 
distilled  water,  and  then  filtered  if  necessary.  A  few  drops  of  dilute 
hydrochloric  acid  are  added,  and  the  solution  again  filtered  if  neces- 
sary. Strips  of  the  woolen  cloth  are  placed  in  the  solution,  which  is 
boiled  for  five  to  ten  minutes.  The  cloth  is  removed  and  washed 
in  water  and  boiled  in  very  dilute  hydrochloric  acid.  The  coloring 
matter  naturally  present  in  fruits  generally  imparts  a  dull  color  to 
the  cloth,  while  aniline  dyes  produce  bright  shades. 

As  a  further  test  the  color  is  dissolved  by  boiling  the  cloth  in  a 
dilute  solution  of  ammonia  made  by  adding  a  few  drops  of  strong 
ammonia  to  25  ccm.  of  water.  When  no  more  solvent  action  is  ob- 
served, the  cloth  is  removed,  the  solution  is  made  acid,  and  a  fresh 
piece  of  woolen  cloth  boiled  in  the  solution.  If  the  second  piece  of 
woolen  cloth  is  dyed,  aniline  dyes  are  present. 

Frequently  with  whole  fruit  like  cherries  the  coloring  matter  is 
present  in  the  solid  particularly.  When  this  is  the  case,  the  liquor 
should  be  drained  off  and  the  finely  divided  fruit  warmed  with  three 
times  its  bulk  of  alcohol  until  the  color  is  sufficiently  extracted. 
The  mixture  is  then  filtered,  and  after  diluting  the  filtrate  with 
twice  the  volume  of  water  and  acidifying  with  hydrochloric  acid,  the 
wool  is  dyed  as  already  directed. 


CHAPTER  XIV 

FRESH  AND  CANNED  VEGETABLES 

Composition  of  vegetables.  Vegetables  are  very  similar 
in  composition  to  fruits.  They  contain  about  the  same  per- 
centage of  water  and  solids  and  have  the  same  calorific  or 
energy  value.  They  differ  from  fruits  in  that  the  main 
constituent  is  starch,  while  sugar  is  the  most  important 
constituent  of  fruits.  For  this  reason,  vegetables  must,  as 
a  general  rule,  be  cooked  before  being  eaten,  while  ripe 
fruit  may  be  eaten  raw.  If  vegetables  are  baked,  the  starch 
is  to  a  greater  or  less  extent  converted  into  sugar,  giving  a 
sweeter  taste.  Vegetables  are  more  easily  stored  and  kept 
in  good  condition  because  starch  is  a  very  stable  substance. 
If  they  are  allowed  to  sprout,  however,  the  starch  is  rap- 
idly converted  into  sugar  and  the  vegetable  soon  decays. 
Vegetables  also  differ  from  fruits  in  containing  little  or 
no  acid,  but  decidedly  more  mineral  matter.  The  table 
on  page  156  gives  the  composition  of  a  number  of  common 
vegetables. 

Water  in  vegetables.  In  spite  of  its  name,  watermelon 
does  not  contain  the  largest  percentage  of  water.  Aspara- 
gus, lettuce,  celery,  and  pumpkins  contain  a  larger  percent- 
age, while  cucumbers  contain  the  largest  amount  of  this 
constituent.  Corn,  peas,  and  potatoes  contain  the  least 
proportion  of  water,  and  therefore  are  the  most  nourishing 
of  vegetables. 

Adulteration  of  vegetables.  There  is  very  little  opportu- 
nity for  fraud  or  adulteration  in  the  sale  of  vegetables,  as 

155 


156 


PUEE  FOODS 


TABLE  XXVII 
Composition  of  Vegetables 


Vegetable 

Water 

Starch 

Sugar 

Protein 

Ash 

Calories 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Asparagus     .... 

93.6 

2.55 

1.83 

0.67 

105 

Beans    .    . 

87.23 

7.52 

2.20 

0.76 

195 

Beets     .    . 

88.47 

7.94 

1.53 

1.04 

215 

Cabbage    . 

90.52 

3.85 

2.39 

1.42 

145 

Carrot  .    . 

88.59 

7.56 

1.14 

1.02 

210 

Celery   .    . 

94.50 

3.5 

1.25 

0.60 

85 

Corn      .    . 

73.00 

13.50 

6.00 

5.00 

0.70 

470 

Cucumber 

95.09 

1.83 

0.81 

0.46 

85 

Lettuce     . 

93.63 

2.18 

1.41 

1.61 

90 

Onion    .    . 

87.55 

9.53 

1.40 

0.57 

225 

Parsnip 

80.34 

16.09 

1.35 

1.03 

300 

Peas       .    . 

79.93 

13.30 

3.87 

0.78 

465 

Potatoes,  Irish 

75.00 

19.87 

0.77 

2.00 

1.00 

400 

sweet 

70.27 

24.00 

6.81 

2.41 

1.14 

570 

Pumpkins 

93.39 

3.93 

0.91 

0.67 

125 

Watermelon 

91.87 

6.65 

0.40 

0.33 

150 

they  are  generally  sold  in  their  natural  state.  Canned  vege- 
tables may  contain  deleterious  ingredients.  Canned  aspara- 
gus and  mushrooms  are  frequently  bleached  by  means  of 
sulphurous  acid.  The  green  color  of  canned  peas,  etc.  is 
frequently  preserved  with  copper  sulphate.  As  this  is  a 
violent  poison,  only  minute  quantities  can  be  taken  with 
foods  without  danger.  The  sale  of  foods  contaming  this 
coloring  matter  is  permitted  if  the  amount  present  is  not 
excessive  and  its  presence  is  stated  on  the  label. 

Desiccated  vegetables.  It  is  possible,  by  means  of  recently 
improved  methods  of  drying,  to  produce  desiccated  vege- 
tables, which,  when  soaked  in  water,  regain  the  taste  and 
other  properties  of  fresh  vegetables.  If  kept  in  a  dry  place, 
such  desiccated  vegetables  will  keep  indefinitely,  and  can 


FRESH  AND  CANNED  VEGETABLES  157 

readily  be  transported,  as  they  are  very  light  on  account 
of  the  absence  of  the  large  amount  of  water  present  in  their 
natural  condition. 

Catsup.  This  is  a  sauce  made  from  tomatoes  and  various 
spices.  A  great  variety  of  substances  have  been  used  in 
making  some  of  the  catsups  which  have  been  placed  on  the 
market.  Turnips  and  other  cheaper  vegetables  and  corn 
meal  have  been  substituted  for  the  tomatoes,  the  red  color 
being  obtained  by  the  addition  of  aniline  dyes.  When  toma- 
toes have  been  used,  they  have  commonly  been  preserved 
with  sodium  benzoate  or  other  preservatives.  Inferior  or 
old  tomatoes  could  be  utilized  by  the  addition  of  the  pre- 
servative. Before  the  recent  national  Pure  Food  Law  was 
enacted,  practically  all  of  the  catsup  sold  contained  a  pre- 
servative. Since  then  methods  have  been  developed  for 
the  preparation  and  marketing  of  tomato  catsup  without 
a  preservative,  sterilization  by  means  of  heat  being  substi- 
tuted. Such  catsup  cannot  be  sold  in  bulk,  but  must  be  put 
up  in  bottles  and  must  be  used  within  a  short  time  of  open- 
ing the  bottle. 

EXPERIMENTS 

32.  Testing  for  sulphur  dioxide.  Test  canned  asparagus,  mush- 
rooms, or  other  light-colored  canned  vegetables  for  sulphur  dioxide 
by  the  methods  given  in  Experiment  21. 

33.  Testing  for  copper  sulphate.  Canned  peas,  beans,  or  spinach 
may  be  tested  for  the  presence  of  copper  sulphate  as  follows :  A  few 
cubic  centimeters  of  the  liquid  portion  are  acidified  with  hydrochloric 
acid  and  filtered.  To  the  clear  solution  a  few  drops  of  barium  chloride 
solution  are  added.  A  white,  finely  divided  precipitate,  which  settles 
slowly,  indicates  the  presence  of  sulphuric  acid,  formed  by  the  decom- 
position of  copper  sulphate.  This  test  will  frequently  fail  with  all 
except  spinach,  because  the  vegetables  have  generally  merely  been 
dipped  in  a  copper  sulphate  solution  and  then  drained. 

From  25  to  50  gm.  of  the  solid  portion  of  the  canned  vegetable 
are  placed  in  a  porcelain  or  platinum  dish  and  heated  gently.    After 


158  PURE  FOODS 

the  moisture  has  been  expelled  the  heat  is  increased  until  the  mate- 
rial begins  to  burn.  When  only  charcoal  remains,  the  dish  is  allowed 
to  cool  and  the  residue  is  moistened  with  not  more  than  3  ccm.  of 
concentrated  nitric  acid  and  warmed  for  a  few  minutes.  After  adding 
25  to  50  ccm.  of  water  the  charred  mass  is  well  stirred  and  filtered. 
If  copper  sulphate  has  been  used,  the  copper  will  be  present  in  the 
nitric  acid  solution.  A  portion  of  the  solution  is  neutralized  with 
ammonia  and  a  slight  excess  added.  If  copper  is  present,  the  solu- 
tion will  be  blue.  After  observing  the  color,  acetic  acid  is  added  until 
the  solution  is  again  acid,  and  a  few  drops  of  potassium  ferrocyanide 
solution  are  then  added.    A  wine-red  color  indicates  copper. 

The  copper  in  the  remainder  of  the  nitric  acid  solution  may  be 
plated  on  platinum  foil  as  follows  :  A  few  cubic  centimeters  of  dilute 
sulphuric  acid  are  added  and  a  small  piece  of  platinum  foil  is  sus- 
pended by  a  platinum  wire  in  the  solution.  Another  platinum  wire  or 
foil  is  suspended  in  the  solution,  care  being  taken  that  it  does  not 
touch  the  first  piece  of  platinum.  The  two  wires  are  connected  with 
an  electric  circuit  in  such  a  way  that  the  platinum  foil  is  attached 
to  the  negative  wire  of  the  circuit.  Electric  batteries  or  a  direct 
electric-lighting  circuit  may  be  used.  In  a  few  hours  the  copper  will 
be  deposited  on  the  platinum  foil  and  may  be  easily  seen  by  its 
red  color. 

If  all  the  nitric  acid  solution  from  a  weighed  amount  of  the  canned 
vegetable  is  used,  and  the  platinum  foil  is  weighed  before  and  after 
the  copper  is  deposited,  the  amount  of  copper  or  copper  sulphate  in 
the  vegetables  may  be  ascertained.  By  multiplying  the  weight  of 
copper  obtained  by  4,  the  weight  of  copper  sulphate  will  be  obtained. 
Although  the  copper  was  added  as  copper  sulphate,  it  is  not  present 
as  such  in  the  vegetable,  but  is  combined  with  the  organic  matter, 
presumably  with  the  protein.  For  further  details  on  making  the 
determination,  the  author's  textbook,  "Quantitative  Chemical  Anal- 
ysis," may  be  consulted. 

34.  Testing  for  aniline  dyes.  Canned  tomatoes  or  other  canned 
vegetables  which  are  suspected  to  have  been  colored  with  aniline 
dyes  may  be  tested  by  the  method  given  in  Experiment  31. 


CHAPTER  XV 

BREAD  AND  THE  CEREALS 

Bread  an  ideal  food.  In  many  ways  bread  is  an  ideal 
food.  It  contains  all  the  elements  necessary  to  sustain  life, 
although  it  is  somewhat  deficient  in  fat.  For  this  reason 
it  is  generally  eaten  with  butter  or  other  food  rich  in  fat. 
The  physical  form  of  bread  is  such  that  with  proper  masti- 
cation the  digestive  fluids  readily  penetrate  the  mass.  It 
does  not  digest  rapidly,  but  gradually,  and  thus  meets  the 
needs  of  the  system  for  nourishment,  without  the  necessity 
of  eating  frequently.  Bread  is  classed  as  a  staple  food  be- 
cause it  can  be  consumed  by  all  human  beings  without  any 
ill  effects.  An  exclusive  diet  of  bread  would,  of  course, 
become  very  distasteful,  as  the  needs  of  the  human  system 
seem  to  be  best  met  by  a  mixed  and  varied  diet. 

Gluten.  Bread  can  be  best  made  only  from  wheat  and 
rye  flour,  on  account  of  the  peculiar  property  of  the  gluten 
or  protein  of  these  grains.  It  has  the  property  of  absorbing 
nearly  three  times  its  weight  of  water  and  forming  a  viscous, 
sticky,  tough,  and  elastic  mass.  The  carbon  dioxide  gas  pro- 
duced by  the  action  of  yeast  distends  this  elastic  mass,  which 
hardens  during  the  baking  and  leaves  the  bread  light  and 
porous.  As  corn  and  other  cereals  cannot  form  such  an 
elastic  mass,  they  cannot  be  used  for  making  bread.  Wheat 
and  rye  contain  a  large  percentage  of  protein,  namely  10 
to  14  per  cent,  while  Indian  corn,  barley,  and  buckwheat 
contain  only  from  7  to  9  per  cent.  As  the  nitrogenous  con- 
stituent of  foods  is  the  most  difficult  to  produce  and  the 

159 


160  PUEE  FOODS 

most  expensive,  this  larger  percentage  of  protein  in  wheat 
gives  it  a  decidedly  greater  value  as  a  food. 

The  following  table  gives  the  average  composition  of 
wheat  flour: 

TABLE  XXVIII 
Composition  of  Wheat  Flour 

Per  cent 

Protein  or  gluten 10-13 

Starch 75 

Fat 1-11 

Ash  or  mineral  matter i-l 

Water    .        10-12 

Grades  of  flour.  The  relative  amounts  of  protein  and 
starch  vary  with  the  kind  of  wheat  and  the  soil  and  climate 
in  which  the  wheat  is  grown.  The  protein  and  starch  are 
also  unequally  distributed  in  the  grain,  the  percentage  of 
protein  being  greatest  near  the  hull  and  least  in  the  center, 
where  the  percentage  of  starch  is  greatest.  The  various 
grades  of  flour  on  the  market  differ  in  composition  not  only 
because  made  from  different  grades  of  wheat,  but  also 
because  made  from  different  portions  of  the  kernel  of  the 
wheat.  The  patent  or  middlings  flour,  which  constitutes  by 
far  the  largest  part  of  the  flour  produced,  contains  less 
protein  and  ash  and  more  starch  than  bakers'  or  family 
flour,  of  which  only  about  one  fourth  as  much  is  produced. 
The  hulls  of  the  grain  constitute  the  bran,  which  contains 
0.8  per  cent  of  mineral  matter  and  as  high  as  15  per  cent 
of  protein,  and  is  used  as  cattle  food. 

Graham  and  whole-wheat  flour.  These  flours  contain  the 
entire  kernel  of  the  wheat,  and  by  bolting  could  be  separated 
into  bran,  patent,  and  family  flour.  The  percentage  of  asli 
or  mineral  matter,  as  well  as  protein,  is  therefore  consider- 
ably higher  than  in  the  finer  or  bolted  grades  of  flour.    For 


BREAD  AND  THE  CEREALS  161 

this  reason  the  claim  has  often  been  made  that  whole-wheat 
and  Graham  bread  constitute  a  more  nutritious  diet  than 
bread  made  from  bolted  flour.  Careful  dietary  experiments 
have  proved  this  idea  to  be  erroneous.  It  has  been  shown 
that  the  system  is  unable  to  assimilate  as  large  a  proportion 
of  the  mineral  and  protein  matter  of  whole-wheat  flour  as 
of  the  finer  grades,  so  that  from  a  given  weight  of  bread  the 
same  amount  of  nourishment  can  be  derived,  whether  made 
of  bolted  or  unbolted  flour.  In  addition  it  appears  that  the 
coarser  particles  of  bran  in  the  whole-wheat  flour  have  an 
irritating  effect  in  many  cases  on  the  delicate  lining  of  the 
digestive  tract. 

Bleached  flour.  Wheat  flour  is  subject  to  some  adulter- 
ation. Inferior  grades  of  wheat  flour  are  at  times  mixed 
with  or  sold  as  superior  grades.  This  practice  has  become 
more  common  since  the  processes  of  bleaching  flour  have 
been  introduced.  The  grade  or  quality  of  flour  is  largely 
determined  by  its  appearance,  odor,  and  color,  as  well  as  by 
its  fineness,  as  indicated  by  rubbing  between  the  fingers.  A 
very  minute  amount  of  nitric  oxide  will  remove  the  yellow 
tint  of  an  inferior  grade  of  flour,  so  that  it  can  be  sold  as  a 
much  higher  grade.  The  sale  of  bleached  flour  is  therefore 
generally  held  to  be  illegal.  The  bread-making  qualities  of  a 
sample  of  flour  may  be  ascertained  by  a  test  of  the  tenacity 
and  elasticity  of  the  dough  produced  from  the  flour.  This  is 
an  important  test  in  the  hands  of  an  experienced  person. 

Mixed  flour.  Flour  made  from  other  grains  is  sometimes 
mixed  with  wheat  flour.  Corn  and  barley  flour  have  been 
used  as  adulterants  in  this  manner.  These  foreign  flours 
are  detected  by  a  microscopic  examination.  The  starch 
grains  of  wheat  are  circular  and  of  two  sizes,  the  larger 
having  a  diameter  of  0.021  to  0.041  mm.  and  are  marked 
with   concentric  rings,   while  the   smaller  grains   have  a 


162  PUKE  FOODS 

diameter  of  about  0.005  mm.  The  starch  grains  of  the 
other  cereals  are  of  a  different  size  and  appearance. 

Other  flours  than  wheat.  Flour  made  from  other  grains 
than  wheat  is  less  used  and  differs  m  composition  from 
wheat  flour  to  a  considerable  extent.  Rye  flour  contains  a 
larger  percentage  of  protein,  ash,  and  crude  fiber  than  wheat 
flour.  It  is  also  much  coarser  and  makes  a  darker-colored 
bread.  Indian  corn  flour  contains  only  about  7  per  cent  of 
protein  and  a  higher  content  of  starch  and  fat  than  wheat 
flour.  The  protein  does  not  form  the  tough  elastic  mass  so 
characteristic  of  the  gluten  of  wheat  flour.  Barley  flour  is 
similar  in  composition  to  corn  flour  but  contains  less  fat. 
Buckwheat  flour  contains  a  relatively  large  amount  of  fat 
and  has  only  a  small  percentage  of  protein. 

The  raising  of  bread.  Bread  is  any  baked  mixture  of  any 
kind  of  flour  and  water  with  or  without  a  leavening  agent. 
By  bread  is  generally  understood  that  made  from  wheat  or 
rye  flour.  While  at  times  the  dough  is  raised  by  a  chemical 
substance,  such  as  backing  powder,  the  great  bulk  of  the 
bread  used  is  raised  by  means  of  yeast.  Chemically  the 
bread  produced  by  means  of  yeast  is  slightly  different  from 
that  raised  by  means  of  baking  powder.  A  small  percentage 
of  soluble  carbohydrates  is  present  in  flour  and  dough.  The 
yeast  acts  on  this  material,  converting  it  into  alcohol  and 
carbon  dioxide  gas,  which  becomes  entangled  in  the  gluten 
and,  by  expanding  when  heated,  raises  the  bread.  Although 
a  portion  of  the  alcohol  escapes  during  the  bakmg,  fresh 
bread  contains  a  small  amount  of  alcohol.  Baking  powder 
does  not  bring  about  any  decomposition  of  this  kind.  Dur- 
ing the  process  of  baking,  a  small  percentage  of  the  starch 
is  rendered  soluble  by  being  converted  into  dextrin  and 
invert  sugar,  which  gives  a  slightly  sweet  taste  to  the  bread, 
especially  the  crust. 


BREAD  AKD  THE  CEREALS       163 

Water  in  bread.  A  common  method  of  making  cheap 
bread  consists  in  introducing  more  than  the  normal  amount 
of  water.  Well-made  bread  should  contain  from  33  to  40 
per  cent  of  water.  A  poor  quality  of  bread  will  contain 
from  40  to  48  per  cent  of  water.  Bread  contaming  this 
amount  of  water  tends  to  become  moldy.  Another  com- 
mon method  of  defrauding  the  customer  consists  in  selling 
light-weight  loaves.  The  loaves  on  the  market  differ  very 
much  in  weight,  many  of  them  being  lighter  than  the 
standard  pound  weight. 

Adulteration  of  bread.  Aside  from  adding  too  much 
water,  using  an  inferior  grade  of  flour,  and  making  light- 
weight loaves,  other  adulterations  of  bread  are  rarely 
practiced.  Gypsum,  chalk,  bone  ash,  and  other  minerals 
cannot  be  added  to  bread  without  visibly  affecting  its 
quality.  The  use  of  alum  to  improve  the  appearance  of 
bread  made  from  inferior  flour  is  not  very  common.  Sul- 
phate of  copper  has  also  been  used  to  a  limited  extent  for 
the  same  purpose. 

Adulteration  of  cake.  Cake  differs  from  bread  chiefly  in 
the  addition  of  eggs,  sugar,  butter,  spices,  and  flavoring 
matter.  Some  of  these  ingredients  are  subject  to  consider- 
able adulteration,  while  frequently  very  inferior  grades  are 
used  in  cake  because  the  consumer  has  no  means  of  judging 
the  quality  of  the  ingredients.  Owing  to  the  cost  and  diffi- 
culty of  obtaining  fresh  eggs,  the  temptation  is  very  great 
to  use  some  form  of  preserved  eggs.  No  objection  can  be 
raised  to  the  use  of  cold-storage  eggs  in  good  condition, 
or  a  good  grade  of  desiccated  eggs.  This  cannot  be  said 
of  the  liquid  eggs  which  have  been  used  to  a  considerable 
extent.  Such  eggs  have  been  broken  and  the  liquid  por- 
tion separated  from  the  shells.  By  the  addition  of  a  pre- 
servative, such  as  borax  or  formaldehyde,  such  eggs  could 


164  PURE  FOODS 

be  transported  in  open  casks  from  China  to  New  York. 
Eggs  which  have  become  so  badly  decomposed  as  to  be 
unsalable  could  be  rendered  odorless  by  the  addition  of 
formaldehyde.  Through  the  activity  of  the  state  and  na- 
tional health  authorities  the  sale  of  such  eggs  has  been 
largely  prevented. 

Egg  substitute.  The  addition  of  the  requisite  number  of 
eggs  for  a  given  cake  is  often  entirely  omitted  and  their 
absence  masked  by  the  addition  of  the  requisite  amount  of 
some  coloring  matter.  If  a  portion  only  of  the  eggs  is 
omitted,  enough  coloring  matter  is  added  to  give  the  color 
produced  by  the  full  number  of  eggs.  This  deception  is 
possible  because  the  consumer  considers  the  yellow  color 
evidence  of  the  presence  of  eggs.  Such  yellow  coloring  is 
often  sold  under  the  name  of  ''  egg  substitute." 

BreaMast  foods.  The  cereals  are  also  consumed  in  large 
quantities  in  the  form  of  breakfast  foods.  They  differ  very 
little  in  composition  from  the  cereal  from  which  they  are 
made.  By  various  processes,  such  as  steaming,  roasting,  or 
baking,  the  starch  of  the  cereal  is  rendered  more  soluble 
and  partially  converted  into  sugar,  so  that  the  flavor  is 
improved  and  the  time  required  for  cooking  the  breakfast 
food  is  materially  reduced  or  cooking  rendered  entirely 
unnecessary.  Individuality  is  also  given  to  the  various 
preparations  by  varying  the  size  and  general  appearance 
of  the  grains. 


CHAPTER  XVI 

LEAVENING  AGENTS 

Discovery  of  yeast.  Bread  is  undoubtedly  one  of  the 
foods  which  has  been  used  for  the  longest  time  by  man. 
In  the  most  primitive  state  of  civilization  cereals  of  various 
kinds  were  crushed  by  means  of  flat  stones  or  crude  mills. 
The  flour  so  made  was  mixed  with  water  and  baked  on 
hot  stoves  into  cakes.  It  was  very  early  discovered  that 
cakes  which  were  allowed  to  remain  for  some  time  before 
baking  were  more  porous  and  palatable,  and  that  this  ob- 
ject was  still  better  attained  by  reserving  a  portion  of  one 
day's  mixing  to  be  kneaded  into  the  fresh  cake  of  the 
following  day. 

The  yeast  plant.  Although  this  process  of  leavening  is 
of  the  greatest  antiquity,  it  is  less  than  a  century  since 
the  nature  of  the  process  was  at  all  understood.  It  is  now 
known  that  leavened  bread  contains  an  enormous  number 
of  microscopic  organisms  known  as  the  yeast  germ  or  plant. 
When  this  plant  grows  and  multiplies,  it  converts  certain 
soluble  carbohydrates  into  alcohol  and  carbon  dioxide.  This 
carbon  dioxide  gas  remains  entangled  in  the  dough,  so  that 
when  heat  is  applied  it  expands  and  causes  the  bread  to  rise. 
A  common  household  method  of  making  bread  lighter  con- 
sists in  adding  to  the  dough  the  water  in  which  potatoes 
have  been  boiled.  This  method  is  effective  because  this 
water  contains  dissolved  starch,  which  is  acted  upon  by 
the  yeast  with  the  production  of  carbon  dioxide.  The  same 
object  is  attained  by  the  addition  of  a  form  of  dextrose 

165 


166  PURE  FOODS 

known  as  bakers'  sugar.  This  is  manufactured  from  corn- 
starch and  is  largely  used  by  the  bakers. 

Sour  bread.  If  the  dough  is  allowed  to  stand  for  too  long 
a  time  or  at  an  unsuitable  temperature,  another  so-called 
ferment  may  become  active  and  convert  the  alcohol  into 
acetic  acid,  thus  making  the  dough  sour.  We  know  now 
that  the  germs  of  these  organisms  are  widely  distributed  in 
nature,  so  that,  unless  the  greatest  care  is  taken  to  exclude 
them,  they  will  be  present  and  set  up  fermentation  in  any 
suitable  organic  matter.  It  is  for  this  reason  that  most  foods 
rapidly  become  sour,  especially  during  warm  weather. 

Raising  bread  by  means  of  carbon  dioxide  gas.  Since  the 
nature  of  the  process  of  raising  bread  was  made  clear,  many 
attempts  have  been  made  to  supplant  the  old-fashioned 
method  of  raising  bread  by  means  of  yeast,  but  so  far  these 
efforts  have  met  with  very  little  success.  As  bread  is  raised 
by  the  expansion  of  the  imprisoned  carbon  dioxide  gas,  the 
attempt  has  been  made  to  force  this  gas  into  the  dough, 
which  for  this  purpose  was  placed  in  steel  cylinders.  An 
attempt  in  London  to  sell  bread  made  by  this  process  did 
not  succeed,  because  the  bread  differed  in  flavor  from  that 
raised  with  yeast. 

Liebig's  method  of  raising  bread.  Attempts  have  been 
made  to  mix  with  the  flour  chemical  substances  which 
would  gradually  liberate  the  carbon  dioxide  gas  necessary 
to  raise  the  bread.  The  distinguished  chemist  Liebig  sug- 
gested that  a  very  suitable  combination  of  this  kind  would 
be  sodium  bicarbonate  and  hydrochloric  (muriatic)  acid. 
By  the  interaction  of  these  substances  the  carbon  dioxide 
needed  would  be  liberated,  and  there  would  also  be  formed 
some  sodium  chloride  or  common  salt,  which  would  be 
necessary  in  any  case  for  the  purpose  of  seasoning  the 
bread.    The  difficulty  in  using  this  process  is  that  it  would 


LEAVENIKG  AGENTS  167 

be  necessary  to  have  an  acid  of  exact  strength,  and  to 
measure  the  acid  as  well  as  the  sodium  bicarbonate  with 
the  greatest  care,  so  that  an  excess  of  neither  substance 
would  be  present.  The  ordinary  cook  or  baker  does  not 
possess  the  intelligence  and  skill  necessary  to  do  this. 

Cream  of  tartar  baking  powders.  A  number  of  other 
acids  have  been  more  largely  used,  sodium  bicarbonate  being 
in  each  case  the  substance  employed  to  furnish  the  carbon 
dioxide  gas.  Acid  potassium  tartrate  or  cream  of  tartar 
has  been  quite  largely  used.  Formerly  these  two  substances 
were  purchased  separately  and  the  proper  quantities  of  each 
measured  out  and  added  to  the  flour  before  mixing  the 
dough,  the  sodium  bicarbonate  being  known  as  saleratus. 
The  use  of  these  substances  separately  has  now  been  very 
largely  superseded  by  the  so-called  baking  powders.  These 
powders  are  simply  mixtures  of  sodium  bicarbonate  and  a 
solid  acid  constituent  like  potassium  bitartrate.  When  such 
a  mixture  is  moistened  with  water,  the  acid  acts  on  the 
bicarbonate  of  soda,  liberating  carbon  dioxide  and  forming 
the  sodium  salt  of  the  acid  constituent.  As  the  moisture 
of  the  air  is  slowly  absorbed  by  the  mixture,  the  baking 
powder  would  slowly  lose  its  carbon  dioxide  and  be  re- 
duced in  strength.  In  order  to  prevent  this  action,  starch 
must  be  added  to  the  mixture. 

Alum  and  phosphate  baking  powders.  A  number  of  other 
acid  substances  are  used  in  baking  powders,  the  most  com- 
mon being  acid  calcium  phosphate  and  alum.  Sodium  bicar- 
bonate must  always  be  present,  as  well  as  starch,  to  prevent 
interaction  between  the  constituents  of  the  powder  until  it 
is  moistened  in  the  process  of  mixing  the  batter.  The  three 
classes  of  baking  powder  are  known  as  tartrate,  phosphate, 
and  alum  powders.  They  are  about  equally  efficient  as 
leavening  agents,  the  constituents  being  combined  in  such 


168  PUKE  FOODS 

proportions  that  they  exactly  neutralize  each  other.  Starch 
is  added  in  a  proportion  sufficient  to  give  powders  of  equiv- 
alent strength,  so  that  a  teaspoonful  of  any  baking  powder 
shall  liberate  the  same  amount  of  carbon  dioxide.  The 
various  powders  on  the  market  differ  somewhat  in  keeping 
qualities  and  also  in  the  relative  rapidity  with  which  the 
carbon  dioxide  is  liberated.  These  properties  may  be  some- 
what modified  by  adding  a  small  amount  of  tartaric  acid  to 
the  tartrate  powders,  as  well  as  by  making  mixed  powders ; 
that  is,  using  two  acid  constituents  in  the  same  powder. 

Objections  to  the  use  of  alum  baking  powders.  The  use 
of  alum  baking  powders  has  met  with  very  considerable 
opposition  on  account  of  the  poisonous  properties  of  alum. 
For  this  reason  the  sale  of  baking  powders  containing 
alum  has  been  prohibited  in  some  states.  It  is  doubtful, 
however,  if  any  alum  is  ever  present  in  the  stomach  after 
bread  or  cake  is  eaten  which  has  been  prepared  with  a 
baking  powder  containing  alum.  This  is  due  to  the  fact 
that  when  such  powders  are  moistened,  the  alum  is  decom- 
posed by  the  sodium  bicarbonate,  with  the  liberation  of 
carbon  dioxide  and  the  formation  of  sodium  sulphate, 
potassium  sulphate,  and  aluminium  hydrate.  While  there 
is  a  possibility  that  by  the  action  of  the  hydrochloric  acid 
of  the  gastric  juice  these  substances  may  again  form  alum, 
it  is  generally  believed  that  this  action  does  not  take 
place  to  any  great  extent.  The  practice  of  adding  alum  to 
flour  in  order  to  produce  a  whiter  bread  is  to  be  con- 
demned. The  substitution  of  ammonia  alum  in  place  of 
the  more  expensive  potash  alum  in  the  manufacture  of  bak- 
ing powders  is  also  reprehensible.  A  great  deal  of  baking 
powder  is  also  made  with  sodium  alum. 

Wholesomeness  of  phosphate  and  tartrate  powders.  No 
objection  of  this  kind  has  been  raised  against  the  phosphate 


LEAVENING  AGENTS  169 

and  the  tartrate  powders.  Phosphorus  in  some  form  is  a 
necessary  constituent  of  our  diet,  although  it  is  doubtful 
if  the  system  can  assimilate  this  element  from  a  phosphate. 
The  tartrate  powders  are  considered  the  most  wholesome 
because  the  acid  is  obtained  from  such  a  commonly  used 
fruit  as  the  grape.  Being  an  organic  acid,  it  can  be  oxy- 
dized  so  as  to  furnish  energy  to  the  human  system.  By  the 
action  of  the  acid  potassium  tartrate  on  sodium  bicarbonate 
when  the  baking  powder  is  used,  the  compound  sodium 
potassium  tartrate,  or  Rochelle  salt,  as  it  is  commonly 
called,  is  formed.  This  salt  has  a  marked  physiological 
action  on  the  system,  being  laxative  in  its  action,  so  that 
if  a  considerable  amount  of  bread  or  cake  which  has  been 
raised  by  a  tartrate  baking  powder  is  consumed,  its  effect 
may  be  quite  serious.  The  use  of  large  quantities  of  bread 
or  cake  raised  with  baking  powder  seems  to  be  attended 
with  some  liability  of  injury  to  the  health,  no  matter  what 
baking  powder  is  used.  The  most  wholesome  bread  is 
undoubtedly  that  raised  by  means  of  yeast. 


EXPERIMENTS 

35.  Testing  baking  powders  for  alum.  The  presence  of  alum  in 
baking  powders  may  be  tested  for  in  the  following  manner :  To  a 
few  grams  of  the  powder  25  ccm.  of  water  is  added.  When  the 
gas  has  escaped,  a  few  cubic  centimeters  of  dilute  hydrochloric  acid 
is  added  and  the  starch  which  is  insoluble  is  filtered  off.  To  a  small 
portion  of  the  filtrate  a  few  drops  of  barium  chloride  solution  are 
added.  A  heavy  white  precipitate  indicates  the  presence  of  sulphates, 
which  constitute  a  portion  of  the  alum. 

To  another  portion  of  the  hydrochloric  acid  solution  caustic  soda 
solution  is  added  drop  by  drop.  A  white  gelatinous  precipitate  may 
be  calcium  phosphate,  aluminium  phosphate,  or  aluminium  hydroxide. 
Caustic  soda  is  added  until  the  solution  is  alkaline,  and  then  a  con- 


170  PUKE  FOODS 

siderable  excess  is  added  and  the  solution  warmed.  If  the  precipitate 
dissolves  entirely,  calcium  is  absent  and  aluminium  is  present,  which 
may  be  confirmed  by  adding  hydrochloric  acid  until  the  solution  is 
acid  to  litmus  paper,  and  then  making  it  alkaline  with  ammonia  and 
warming.  A  white  flocculent  precipitate  proves  the  presence  of  alu- 
minium. If  both  sulphates  and  aluminium  are  found,  alum  was  pres- 
ent in  the  baking  powder.  If  the  precipitate  obtained  with  caustic 
soda  does  not  give  a  clear  solution  with  caustic  soda,  calcium  may 
be  present.  In  that  case  the  solution  is  filtered  and  tested  for  alu- 
minium as  already  directed,  as  the  baking  powder  may  have  been 
prepared  with  both  alum  and  calcium  phosphate. 

Aluminium  may  also  be  tested  for  by  the  following  simple 
method :  Place  2  gm.  of  the  baking  powder  in  a  porcelain  or 
platinum  dish  and  heat  with  the  Bunsen  burner  until  the  powder 
is  burned  to  a  nearly  white  ash.  Extract  with  boiling  water  and 
filter.  To  the  hot  clear  filtrate  add  ammonium  chloride  solution 
until  a  distinct  odor  of  ammonia  is  given  off.  A  white  flocculent 
precipitate  is  evidence  of  the  presence  of  aluminium. 

Another  simple  test  is  carried  out  as  follows:  Logwood  extract 
is  prepared  by  covering  some  logwood  chips  with  water  and  bringing 
to  a  boil.  This  is  repeated  four  times,  the  last  extraction  being  re- 
served for  use.  A  few  grams  of  the  baking  powder  are  treated  with 
water.  AVhen  effervescence  ceases,  the  solution  is  made  strongly 
acid  with  acetic  acid  and  a  few  drops  of  the  logwood  extract  added. 
A  bluish-red  color  indicates  the  presence  of  alum. 

36.  Testing  baking  powders  for  phosphates.  In  order  to  make  the 
test  for  calcium  phosphate,  the  precipitate  obtained  in  Experiment  35, 
which  does  not  dissolve  in  caustic  soda,  may  be  used.  It  is  dissolved 
in  a  few  drops  of  hydrochloric  acid,  a  few  cubic  centimeters  of  ammo- 
nium oxalate  are  added,  and  the  solution  made  alkaline  with  am- 
monia. A  finely  divided  white  precipitate  is  evidence  of  the  presence 
of  calcium. 

In  order  to  test  for  phosphoric  acid,  a  fresh  portion  of  the  baking 
powder  is  treated  with  water  and  the  starch  filtered  off.  Equal  vol- 
umes of  dilute  nitric  acid  and  ammonium  molybdate  solution  are 
added  and  the  mixture  thoroughly  shaken  or  stirred.  A  yellow,  finely 
divided  precipitate  which  forms  somewhat  slowly  is  evidence  of  the 
presence  of  a  phosphate.  If  calcium  has  also  been  found,  the  pres- 
ence of  calcium  phosphate  has  been  proved. 


LEAVENING  AGENTS  171 

37.  Testing  baking  powders  for  tartaric  acid.  A  baking  powder 
may  be  tested  for  the  presence  of  tartaric  acid  as  follows  :  A  solution 
of  resorcin  in  sulphuric  acid  is  prepared  by  dissolving  1  gm.  in 
50  gm.  of  concentrated  sulphuric  acid.  Five  gm.  of  the  baking  pow- 
der are  treated  with  250  ccm.  of  cold  water.  After  allowing  the  car- 
bon dioxide  gas  to  escape  and  shaking  thoroughly  for  a  few  minutes, 
the  starch  is  filtered  off  and  the  filtrate  evaporated  to  dryness  on 
a  water  or  steam  bath  so  as  to  avoid  charring  the  tartaric  acid. 
A  portion  of  the  dry  residue  is  treated  with  a  few  cubic  centimeters 
of  sulphuric  acid  solution  of  resorcin  and  warmed  until  the  white 
fumes  of  sulphuric  acid  just  begin  to  appear.  If  tartaric  acid  is 
present,  the  liquid  assumes  a  beautiful  wine-red  color.  The  color 
disappears  on  the  addition  of  water.  As  concentrated  sulphuric  acid, 
especially  when  hot,  reacts  rather  violently  with  water,  the  acid 
should  be  allowed  to  cool  and  the  water  added  very  slowly. 

Another  portion  of  the  dry  residue  obtained  from  the  water  ex- 
tract of  the  baking  powder  may  be  tested  as  follows :  The  dry  resi- 
due is  dissolved  in  a  few  cubic  centimeters  of  water,  transferred  to 
a  clean  test  tube,  and  a  few  drops  of  silver  nitrate  solution  added. 
On  shaking  for  a  few  minutes  a  white  crystalline  precipitate  is 
formed  if  tartaric  acid  is  present.  Dilute  ammonia  is  added  drop  by 
drop  until  the  precipitate  is  dissolved.  The  solution  is  diluted  some- 
what and  the  test  tube  placed  in  warm  water.  If  a  mirror  of  metallic 
silver  is  formed  on  the  test  tube,  the  presence  of  tartaric  acid  is  in- 
dicated. A  brown  precipitate  of  metallic  silver  is  also  generally 
formed  in  the  solution.  If  the  test  tube  is  not  perfectly  clean  or  the 
water  too  hot,  the  mirror  may  not  form  and  only  the  brown  precipi- 
tate be  produced.  It  is  advisable  to  carry  out  preliminary  experiments 
on  pure  cream  of  tartar  or  tartaric  acid,  in  order  to  become  familiar 
with  the  method  before  making  the  test  on  a  baking  powder. 


CHAPTER  XVII 

SPICES  AND  CONDIMENTAL  FOODS 

Importance  of  spices  in  the  diet.  Substances  which  are 
added  to  foods  simply  to  give  an  agreeable  flavor  are  called 
condimental  foods.  In  most  cases  their  nutritive  value  is 
very  slight.  They  are  of  importance  in  the  diet  because 
they  serve  to  stimulate  the  appetite  and  increase  the  flow 
of  the  digestive  fluids.  The  digestive  organs  are  to  such 
an  extent  controlled  by  the  nervous  system,  that  in  many 
cases  little  or  no  digestion  takes  place  if  food  is  introduced 
into  the  stomach  in  such  a  manner  that  the  individual  is 
not  aware  of  being  fed.  This  experiment  has  been  re- 
peatedly tried  on  animals.  It  has  long  been  known  that 
hasty  eating,  with  little  or  no  consciousness  of  the  food 
being  eaten,  leads  to  indigestion.  While  many  explanations 
have  been  given  for  this  observation,  probably  one  of  the 
most  important  ones  is  the  fact  that  under  these  circum- 
stances the  digestive  organs  are  not  properly  stimulated. 

Digestion  stimulated  by  attractive  foods.  It  is  for  a 
similar  reason  that  the  preparation  of  food  so  as  to  make  it 
attractive  in  appearance  is  important.  The  color  and  odor 
as  well  as  the  taste  of  food,  and  pleasing  surroundings,  all 
tend  to  arouse  the  appetite,  stimulate  the  flow  of  the  di- 
gestive fluids  and  increase  their  strength. 

Origin  of  condiments.  Almost  all  substances  used  as 
condiments  are  of  vegetable  origin,  the  seeds,  fruits,  buds, 
flowers,  bark,  or  roots  being  taken,  depending  upon  the  part 
of  the  plant  which  contains  the  aromatic  principle.    In 

172 


SPICES  AND  CONDIMENTAL  FOODS  173 

many  cases  the  flavor  of  the  pure  substance  is  not  agreeable, 
but  becomes  so  when  added  in  proper  quantity  to  other 
foods.  Frequently  a  still  finer  flavor  is  obtained  when 
several  condimental  substances  are  blended  in  foods,  because 
a  combination  of  several  flavors  seems  to  be  most  agreeable 
to  the  palate.  Similarly,  it  has  been  found  that  the  natural 
flavor  of  vegetable  substances  is  generally  due  to  the  pres- 
ence of  several  chemical  compounds,  many  of  which  are 
volatile  oils.  In  many  cases  these  oils  can  be  separated  in 
pure  form,  such  as  clove,  lemon,  mustard,  nutmeg  oil,  etc. 
Being  volatile,  they  give  agreeable  odors,  and  if  condiments 
are  added  to  hot  or  boiling  foods,  much  of  the  flavor  is  lost. 

Allspice.  This  spice  is  the  dried  fruit  of  an  evergreen 
tree  which  grows  in  the  West  Indies  and  is  especially  cul- 
tivated in  Jamaica.  The  berries  are  gathered  before  they 
are  fully  ripe,  as  at  this  stage  they  give  the  best  aroma.  If 
the  dried  berry  is  broken  open,  it  is  found  to  consist  of  two 
cells,  each  of  which  contains  a  single  seed.  The  principal 
constituents  of  allspice  are  a  volatile  oil  (which  produces 
the  characteristic  flavor),  starch,  tannin,  mineral  matter, 
protein,  and  crude  fiber. 

Cinnamon,  or  cassia,  as  it  is  often  called,  is  the  bark  of  a 
tree  which  is  cultivated  in  the  islands  of  Ceylon,  Sumatra, 
and  Java,  as  well  as  in  some  parts  of  tropical  Asia.  The 
thin  inner  bark  of  the  tree  is  used,  and  comes  into  commerce 
in  long  cylindrical  rolls  of  a  brownish-yellow  color.  A 
cheaper  grade,  which  is  generally  called  cassia,  is  the  bark 
of  a  tree  which  grows  in  China,  Indo  China,  and  India.  As 
the  outer  bark  is  usually  left  on,  this  product  is  thicker  and 
heavier  than  the  Ceylon  cinnamon.  It  is  also  of  a  darker 
color  and  coarser  texture.  Cassia  buds  are  also  found  on 
the  market,  both  whole  and  powdered,  and  are  the  dried 
flower  buds  of  the  China  cassia. 


174  PURE  FOODS 

The  flavor  of  cinnamon  is  due  to  the  presence  of  from  1  to 
2  per  cent  of  a  volatile  oil  which  has  a  very  pungent  and 
intensely  sweet  taste.  A  somewhat  bitter  taste  is  due  to  the 
presence  of  a  small  amount  of  tannin.  Other  constituents 
are  starch  (16-30  per  cent),  crude  fiber,  ash,  protein, 
and  water. 

Cloves  are  the  dried  undeveloped  flowers  of  the  clove 
tree.  This  is  an  evergreen  tree  which  is  cultivated  in  Brazil, 
Ceylon,  India,  the  West  Indies,  and  other  tropical  countries. 
When  the  green  buds  begin  to  turn  red,  they  are  gathered 
and  dried  in  the  sun.  They  then  acquire  a  deep  brown 
color.  On  close  examination  of  the  clove,  the  four  branch- 
ing sepals  can  be  seen  surrounding  the  overlapping  petals 
which  inclose  the  stamens  and  pistil  of  the  flower. 

Composition  of  cloves.  The  strong  pungent  odor  and  taste 
is  due  to  the  volatile  clove  oil,  of  which  from  10  to  20  per 
cent  is  present.  The  astringent  taste  is  due  to  tannin,  of 
which  about  18  per  cent  is  present.  Mineral  matter,  starch, 
crude  fiber,  and  protein  constitute  the  remainder  of  the 
composition  of  cloves. 

Cayenne  pepper  is  the  dried  fruit  pods  of  an  herb  which  is 
cultivated  in  all  temperate  and  tropical  regions  of  the  earth. 
A  large  number  of  species  of  the  plant  are  known  and 
cultivated,  giving  pepper  varying  considerably  in  color  and 
pungency  of  flavor.  The  cayenne  and  chili  varieties  give 
long  and  slender  pods  of  great  pungency.  The  Hungarian 
red  pepper  is  known  as  paprika^  and  is  a  very  mild  variety. 

Composition  of  cayenne.  While  cayenne  contains  a  small 
amount  of  oil,  the  pungent  taste  of  this  pepper  is  due  to 
the  presence  of  an  alkaloid  known  as  capsiein.  The  red 
coloring  matter  which  is  present  in  the  pod  is  an  important 
constituent.  Fiber,  ash,  protein,  etc.,  constitute  the  remain- 
der of  the  pepper. 


SPICES  AND  CONDIMENTAL  FOODS  175 

Ginger  is  the  rootstock  of  an  herb  which  grows  to  a  height 
of  from  three  to  four  feet.  It  is  cultivated  very  extensively 
in  India,  China,  tropical  America,  Africa,  and  Australia. 
Most  of  the  ginger  of  commerce  comes  from  Calcutta.  When 
the  plant  is  a  year  old  and  the  stem  has  withered,  the  root 
is  dug  up.  By  different  treatment  of  the  root  black  or 
white  ginger  is  produced.  If  the  root  when  freshly  dug  is 
scalded  to  prevent  sprouting  and  is  dried  at  once,  black 
ginger  is  produced.  If,  on  the  other  hand,  the  bark  is 
removed  to  prevent  sprouting,  white  ginger  is  produced.  It 
is  sometimes  made  still  whiter  by  bleaching  or  sprinkling 
with  carbonate  of  lime.  The  white  ginger  is  less  aromatic 
and  is  generally  considered  inferior  to  the  black  ginger. 
This  is  largely  due  to  the  fact  that  the  bark  contains  a  large 
amount  of  pungent  resin,  which,  together  with  a  volatile  oil, 
gives  the  characteristic  flavor  to  the  root.  About  2  per  cent 
of  an  aromatic  oil  and  from  3  to  4  per  cent  of  a  fixed  oil 
and  resin  is  present.  The  remaining  constituents  are  starch 
(about  50  per  cent),  crude  fiber,  protein,  ash,  and  water. 

Mustard  is  the  seed  of  an  herb  which  is  cultivated  exten- 
sively throughout  the  United  States  and  Europe.  There 
are  two  varieties,  known  as  white  and  black  mustard, 
although  they  are  often  known  as  yellow  and  brown  mus- 
tard. The  seed  of  black  mustard  is  dark  brown  on  the 
outside  and  yellow  within,  while  that  of  white  mustard  is 
pale  yellow.  The  ground  mustard  is  generally  a  mixture 
of  both  species. 

Composition  of  mustard.  Both  black  and  white  mustard 
contain  valuable  ferments  known  as  myrosin  and  sulpho- 
cyanate  of  sinapine.  Black  mustard  also  contains  sinigrin, 
or  myronate  of  potash,  which  is  not  found  in  white  mus- 
tard, and  which,  upon  being  moistened  with  water  under 
the  action  of  the  ferment  also  present  in  the  seed,  forms 


176  PUEE  FOODS 

the  volatile  oil  of  black  mustard.  White  mustard,  on  the 
other  hand,  contains  a  glucoside,  sinalbin,  not  present  in 
black  mustard,  which  in  the  presence  of  water  and  the  fer- 
ment myrosin  also  forms  by  hydrolysis  an  oil  characteristic 
of  white  mustard. 

Powdering  of  mustard.  In  preparing  the  ground  mus- 
tard the  seeds  are  first  crushed  and  the  hulls  separated 
from  the  meats.  In  order  to  grind  the  latter  a  considerable 
portion  of  the  fixed  oil  must  be  removed.  This  is  done  by 
subjecting  the  crushed  seeds  to  hydraulic  pressure.  The 
press  cake  is  then  powdered. 

Nutmeg  and  mace  are  obtained  from  the  nutmeg  tree, 
which  is  a  native  of  the  Malay  Archipelago.  The  nutmeg 
of  commerce  is  the  seed  obtained  from  the  fruit  of  the  tree. 
When  gathered,  the  seed  is  surrounded  with  a  thick  cover- 
ing. It  is  dried  in  the  sun  or  by  artificial  heat  for  about 
two  months.  The  outer  covering  dries  and  becomes  sepa- 
rated from  the  kernel  and  can  be  easily  broken  loose.  It 
is  known  in  commerce  as  mace.  The  nut  is  washed  in  milk 
of  lime  and  dried  or  sprinkled  with  dry  air-slacked  lime. 
This  treatment  is  said  to  prevent  sprouting  and  to  ward  off 
the  attacks  of  insects.  Some  nutmegs  are  sent  into  com- 
merce without  the  lime  treatment,  and  are  known  as  brown 
nutmegs.  Nutmegs  differ  in  shape  from  nearly  spherical  to 
an  elongated  oval  shape. 

Composition  of  nutmegs.  Nutmegs  contain  from  2.5  to 
4  per  cent  of  a  volatile  oil,  31  to  37  per  cent  of  fat,  30 
to  40  per  cent  of  starch,  7  to  10  per  cent  of  crude  fiber, 
about  5^  per  cent  of  albuminoids,  2  to  3  per  cent  of  ash,  and 
4  to  12  per  cent  of  water.  The  composition  of  mace  is  very 
similar  to  that  of  nutmegs. 

Wild  mace.  The  most  common  adulterant  of  mace  is  the 
so-called  false  or  wild  mace,  commonly  known  as  Bombay 


SPICES  AND  CONDIMENTAL  FOODS  177 

mace.  It  is  almost  entirely  devoid  of  odor  and  taste,  and 
therefore  lowers  the  strength  of  true  mace  when  mixed 
with  it. 

Pepper  is  the  dried  berry  of  the  pepper  plant,  which  grows 
in  the  East  Indies  and  other  tropical  countries.  It  is  a 
climbing  shrub,  which  grows  to  a  height  of  from  twelve  to 
twenty  feet.  When  the  fruit  begins  to  turn  red,  it  is 
gathered  and  dried.  It  then  shrivels  up  and  turns'  black. 
There  are  a  good  many  varieties  of  black  pepper  which 
have  been  named  from  the  localities  from  which  they  are 
produced  or  from  which  they  are  shipped,  such  as  Singapore, 
Sumatra,  Malabar,  Penang,  Mangalore,  etc. 

White  pepper.  If  the  pepper  berry  is  allowed  to  ripen 
and  the  skin  removed,  white  pepper  is  produced.  In  some 
cases  white  pepper  is  produced  by  removing  the  skin  from 
black  pepper.  White  pepper  is  named  in  the  same  manner 
as  the  black  varieties,  such  as  Siam,  Singapore,  Penang,  etc. 
The  pungent  taste  of  pepper  is  produced  by  an  essential 
oil  known  as  pepper  oil,  of  which  from  0.5  to  2  per  cent  is 
present.  There  is  also  present  from  6  to  10  per  cent  of  a 
nonvolatile  oil.  The  odor  and  sharp,  biting  taste  of  pepper 
is  partly  due  to  the  presence  of  two  alkaloids,  piperidiyie 
and  piperine,  of  which  about  5  per  cent  is  present.  From  30 
to  60  per  cent  of  starch,  ash,  water,  and  protein  constitute 
the  remainder  of  the  spice. 

Adulteration  of  spices.  On  account  of  their  high  price, 
spices  have  been  subjected  to  a  great  deal  of  adulteration. 
This  is  especially  true  of  powdered  spices,  to  which  a  great 
variety  of  inert  powdered  material  can  be  added  without 
much  fear  of  detection  by  the  average  consumer.  Com- 
monly used  material  of  this  kind  includes  the  ground 
shells  of  most  nuts,  such  as  English  walnuts,  Brazil  nuts, 
almonds,   coconuts,   etc.     Easily  obtained  waste  products 


178  PUKE  FOODS 

of  various  foods,  such  as  cocoa  shells,  buckwheat  hulls, 
ground  olive,  and  date  stones,  are  frequently  used;  while 
spruce,  oak,  and  red-sandalwood  sawdust  has  at  times 
been  found.  A  microscopic  examination  will  frequently 
show  the  presence  of  these  foreign  substances.  A  given 
spice  will  be  mixed  with  the  adulterant,  which  most  nearly 
resembles  it  in  color  and  general  appearance.  In  many  cases 
the  color  is  imitated  by  means  of  a  dye.  Turmeric,  for 
instance,  can  be  used  to  produce  a  color  similar  to  that  of 
mustard.  Starch  and  various  cereal  flours  have  also  been 
considerably  used.  The  ground  bark  of  various  trees,  more 
especially  the  elm,  has  been  used  to  adulterate  ground  cin- 
namon. Ground  pepper  shells,  stems,  and  sweepings  are 
frequently  added  to  ground  pepper.  Such  material  is 
known  in  the  trade  by  the  symbol  "  P.D. "  (pepper  dust), 
and  this  symbol  has  been  adopted  to  designate  any  material 
suitable  for  the  adulteration  of  pepper  or  other  spices.  • 

Grinding  nutmegs.  Ground  nutmegs  are  subjected  to 
a  rather  peculiar  adulteration.  As  it  is  difficult  to  grind 
whole,  sound  nutmegs  on  account  of  the  rather  large 
amount  of  oil  present,  a  special  grade,  known  as  '*  grind- 
ing nutmegs,"  has  been  used  to  some  extent.  These  are 
moldy,  worm-eaten,  fragmentary  nutmegs,  which  are  im- 
ported for  the  purpose  of  grinding.  When  detected,  the 
importation  or  sale  of  such  spices  is  prevented. 

Exhausted  spices.  Although  powdered  spices  are  far 
more  commonly  adulterated  than  the  whole  spice,  some  adul- 
teration of  the  latter  has  been  practiced.  Where  the  oil  or 
other  flavoring  matter  of  a  spice  can  be  extracted  and  sold, 
the  completely  or  partially  exhausted  spice  is  sometimes 
sold.  Aside  from  a  slightly  wrinkled  or  shriveled  condi- 
tion, the  general  appearance  of  such  spices  is  the  same  as 
that  of  spices  which  have  the  full  flavoring  strength.    The 


SPICES  AND  CONDIMENTAL  FOODS  179 

detection  of  this  adulteration  is  more  difficult  when  such 
exhausted  spices  are  mixed  with  those  of  full  strength. 
The  exhausted  spice  is  also  ground  and  mixed  with  the 
ground,  pure  spice,  very  materially  reducing  the  strength 
of  the  latter.  As  there  is  a  good  market  for  clove  oil,  this 
spice  has  been  largely  subjected  to  this  form  of  adultera- 
tion. The  same  is  true  of  ginger,  because  the  extract  of 
this  spice  is  largely  used. 

Microscopic  examination  of  spices.  A  great  many  of  the 
forms  of  adulteration  of  spices  may  be  detected  by  exami- 
nation under  the  microscope.  For  this  purpose  a  magnifi- 
cation of  about  125  diameters  is  sufficient.  Samples  of 
pure  whole  spices  are  ground  and  compared  with  the 
ground  spice  as  purchased. ^ 

iFor  further  information  on  this  subject,  the  reader  is  referred  to 
Winton's  "Microscopy  of  Vegetable  Foods"  and  Leach's  "Food  Inspec- 
tion and  Analysis." 


CHAPTER  XVIII 

FLAVORING  EXTRACTS 

Utility  of  flavoring  extracts.  A  number  of  vegetable 
substances  contain  flavoring  matter  which  can  be  extracted. 
Tliis  is  advantageous  because  such  extracts  are  more  con- 
venient for  use,  and  undesirable  portions  of  the  vegetable 
substances  need  not  be  introduced  into  the  food.  In  some 
cases  both  the  extract  and  the  whole  vegetable  product  is 
in  use.  By  means  of  these  highly  flavored  substances 
many  wholesome  and  nutritious  foods  which  are  quite  lack- 
ing in  flavor  are  made  very  palatable.  Vanilla  and  lemon 
are  by  far  the  most  commonly  used  flavoring  extracts. 

The  vanilla  bean.  Vanilla  extract  is  made  from  the 
vanilla  bean.  This  bean  is  the  fruit  of  the  orchid  Vanilla 
planifolia.  It  is  a  climbing  parasite,  which  fastens  itself  to 
the  bark  of  trees  in  moist  tropical  climates.  It  is  indige- 
nous to  Central  America  and  the  West  Indies,  but  the  finest 
beans  are  produced  in  Mexico.  It  is  frequently  cultivated 
together  with  the  cacao  tree,  as  both  the  vanilla  vine  and 
the  cacao  tree  require  a  rich  soil,  shade  from  large  trees, 
and  a  warm  climate.  While  the  vine  clings  to  the  tree,  it 
obtains  its  nourishment  from  the  air  through  its  tendrils 
and  aerial  rootlets.  It  blossoms  in  October  and  November, 
and  the  pods  are  gathered  in  May,  June,  and  July.  The 
pods  are  green  at  first,  and  when  they  turn  brown  are  ready 
to  be  gathered.  The  drying  of  the  pods  is  the  most  impor- 
tant part  of  their  preparation  for  market,  as  it  is  during 
this  process  that  the  flavor  is  developed.    When  picked, 

180 


FLAVORING  EXTRACTS 


181 


the  beans  are  without  odor,  but  this  develops  during  a  proc- 
ess of  fermentation  or  sweating.  The  drying  in  the  sun 
requires  about  a  month,  and  is  said  to  give  the  best  product. 


Fig.  30.   The  Vanilla  Vine,  showing  Leaves,  Flowers,  and  the 
Vanilla  Beans,  as  well  as  the  Tree  to  which  the  Vine  clings 

Recently  an  artificial  method  of  drying  by  means  of  air 
dried  over  calcium  chloride  has  come  into  use.  This  process 
gives  a  much  more  uniform  product. 


182  PURE  FOODS 

Preparation  of  vanilla  extract.  When  the  curing  and 
drying  process  is  completed,  the  beans  are  tied  in  bundles 
and  sent  to  market,  where  the  best  quality  commands  very 
high  prices,  sometimes  reaching  fifteen  dollars  per  pound, 
although  four  to  six  dollars  is  a  more  common  price.  The 
extract  is  prepared  by  treating  the  beans  with  strong 
alcohol  and  sugar.  For  this  purpose  they  are  cut  up  into 
rather  small  pieces  and  soaked  in  the  alcohol  for  some 
time.  The  alcoholic  extract  is  drained  off  and  bottled  for 
the  market.  To  a  limited  extent  the  beans  are  sold  for  use 
in  foods,  small  portions  being  cut  off  and  put  into  the  food 
to  be  flavored. 

Varieties  of  vanilla  bean.  A  considerable  number  of  dif- 
ferent varieties  and  grades  of  beans  are  found  on  the  market. 
The  Mexican  vanilla  beans  are  considered  the  best,  being 
from  8  to  10  inches  long  and  from  ^  to  ^  inch  thick.  They 
are  dark  brown  in  color  and  feel  waxy  to  the  touch.  The 
Bourbon  beans,  which  are  shorter  than  the  Mexican,  are 
considered  next  in  grade.  They  are  grown  in  the  Isle  of 
Reunion.  Still  shorter  and  cheaper  beans  are  grown  in 
Mauritius  and  South  America.  The  shorter  beans  are 
the  Tahiti  or  wild  vanilla  beans. 

Vanillin.  The  peculiar  flavor  of  the  vanilla  bean  is  very 
largely  due  to  the  presence  of  a  white  crystalline  substance 
which  is  known  as  vanillin.  Crystals  of  this  compound 
may  frequently  be  seen  on  the  outside  of  the  vanilla  beans. 
This  substance  has  been  artificially  prepared  by  chemists 
and  is  manufactured  in  large  quantities.  A  number  of 
other  substances  are  also  present,  which  modify  and  im- 
prove the  flavor.  These  substances  are  known  collectively 
as  resin,  4  to  11  per  cent  being  present  in  vanilla  beans. 
There  are  also  present  considerable  quantities  of  wax,  sugar, 
tannin,  and  gum.     Although  the  flavor  of  the  beans  is 


FLAVORING  EXTRACTS  183 

largely  due  to  the  presence  of  vanillin,  the  most  highly 
prized  varieties  do  not  contain  the  largest  percentage  of 
vanillin,  as  is  shown  by  the  following  table :  ^ 

TABLE  XXIX 

Vanillin  in  Vanilla  Beans 

Per  cent 

Mexican  beans 1.69 

Bourbon  beans 2.48 

Java  beans 2.75 

Pure  vanilla  extract  contains  from  0.1  to  0.2  per  cent  of 
vanillin,  about  20  per  cent  of  sugar,  40  per  cent  of  alcohol, 
and  2  to  4  per  cent  of  other  extractive  matter,  includ- 
ing the  vanilla  resins.  Some  extracts  are  prepared  with 
glycerin  instead  of  sugar. 

The  tonka  bean.  This  bean  has  been  very  largely  used 
in  place  of  the  more  expensive  vanilla  bean  in  making 
extracts.  It  is  the  seed  of  a  large  tree  which  is  native 
to  Guiana.  The  tonka  bean  is  almond-shaped,  and  dark 
brown  or  black.  The  flavoring  matter  in  this  bean  is  an 
entirely  different  substance  from  that  present  in  the  vanilla 
bean.  It  is  known  as  coumarin  and  has  a  much  sharper 
and  less  pleasant  odor  than  vanilla.  It  is  a  white  crystalline 
powder  in  the  pure  state.  The  flavoring  matter  is  ex- 
tracted from  the  tonka  bean  in  exactly  the  same  manner  as 
from  the  vanilla  bean.  The  extract  is  generally  of  a  darker 
color  than  true  vanilla  extract.  It  also  contains  resinous 
matter  somewhat  similar  to  that  of  the  vanilla  bean. 

Tonka  extract.  While  tonka  extract  is  often  sold  as  va- 
nilla extract,  a  much  more  common  practice  consists  in  sub- 
stituting tonka  beans  for  a  portion  of  the  more  expensive 
vanilla  extract.    Both  such  mixed  extracts  and  the  pure 

1  Leach,  Food  Inspection  and  Analysis,  1909,  p.  857. 


184  PURE  FOODS 

tonka  extract  find  a  ready  sale,  because  coumarin,  the  flavor- 
ing matter  of  the  tonka  bean,  has  a  much  sharper  odor, 
giving  the  extract  greater  flavoring  power,  unless  delicacy 
of  flavor  is  desired.  The  sale  of  the  tonka  extract  or  mixed 
tonka  and  vanilla  extract  is  not  illegal  unless  those  prepara- 
tions are  sold  as  pure  vanilla  extract.  They  must  be  labeled 
''Tonka  Extract"  or  "  Tonka  and  Vanilla  Extract,"  so  that 
the  purchaser  clearly  understands  what  he  is  buying. 

Artificial  extracts.  As  both  vanillin  and  coumarin  are 
manufactured  on  a  large  scale  and  can  be  sold  a  great  deal 
cheaper  than  the  natural  flavoring  matter,  a  great  deal  of 
so-called  flavoring  extract  has  been  made  and  sold  which 
contains  no  extract  at  all  of  vanilla  or  tonka  beans.  Such 
artificial  or  compound  extracts  are  prepared  by  dissolving 
vanillin  or  coumarin  crystals  and  sugar  in  alcohol  and 
water  and  adding  some  appropriate  coloring  matter.  Cara- 
mel or  burned  sugar  has  been  very  largely  used  as  coloring 
matter.  Recently  prune  juice,  which  is  an  alcoholic  extract 
of  prunes,  has  been  sold  under  various  trade  names  and 
used  to  some  extent  as  coloring  matter.  In  many  cases  a 
small  quantity  of  vanilla  or  tonka  extract  is  added  to  give 
color  and  flavor. 

The  table  on  page  185  gives  the  composition  of  a  number 
of  vanilla  extracts  as  purchased  on  the  market. 

A  true  vanilla  extract  should  contain  about  38  per  cent 
of  alcohol  and  between  0.1  and  0.2  per  cent  of  vanillin. 
Coumarin  should  be  absent. 

Lemon  extract  is  a  solution  of  the  flavoring  matter  of 
lemon  peel  in  alcohol.  It  is  prepared  by  subjecting  lemon 
peel  to  the  action  of  strong  alcohol.  The  flavoring  matter 
in  the  lemon  peel  is  a  volatile,  fragrant  oil,  which  is  solu- 
ble in  alcohol.  When  pure,  the  oil  is  almost  colorless,  but 
sufl&cient  coloring  matter  is  dissolved   by  the  alcohol  to 


FLAVORING  EXTRACTS 


185 


TABLE  XXX 

Composition  of  Yanilla  Extracts  as  Purchaskd 


Volume  1 

Solids 

Ash 

Alcohol 

Vanillin 

Coumarin 

Ccm. 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

47 

6.55 

0.18 

16.1 

0.095 

12.01 

0.39 

37.7 

0.10 

21.15 

0.84 

28.9 

0.059 

13.52 

13.0 

0.23 

0.38 

12.49 

0.14 

25.37 

0.21 

64 

9.71 

0.09 

15.00 

0.06 

47.5 

7.73 

0.2 

20.00 

0.28 

11.40 

0.05 

18.00 

6.02 

0.03 

14.13 

0.32 

28.30 

0.15 

46 

8.51 

0.29 

23.16 

0.05 

53 

10.72 

10.44 

0.05 

0.07 

4.13 

0.05 

9.85 

0.15 

0.093 

13.25 

0.12 

14.93 

0.15 

0.07 

26.5 

10.70 

0.32 

28.60 

0.10 

56.5 

9.65 

0.45 

45.36 

0.155 

57.5 

14.12 

0.17 

22.35 

1.12 

0.02 

60 

13.10 

0.20 

18.42 

0.27 

57 

14.05 

0.36 

17.01 

0.15 

10.53 

0.02 

9.84 

0.842 

0.07 

10.55 

0.29 

36.7 

0.168 

17 

44.0 

0.50 

18.77 

5.96 

1.82 

give  the  extract  a  light  yellow  color.  The  pure  lemon  oil 
is  prepared  in  large  quantities  from  the  fresh  lemon  peel 
by  pressing  the  peel  against  a  rough  sponge  which  is  kept 
moist  with  water.  As  the  oil  floats  on  the  water,  it  is 
easily  separated  and  purified.  A  great  deal  of  lemon  extract 
is  prepared  by  dissolving  this  oil  in  alcohol  and  coloring 
the  solution  with  a  strong  alcoholic  extract  of  lemon  peel. 
In  some  cases  coal-tar  dyes  or  other  yellow  coloring  matter 

1  Two  ounces  is  equal  to  57  ccm.   The  ordinary  bottle  of  vanilla  extract  is 
understood  to  be  a  two-ounce  bottle. 


186  PURE  FOODS 

is  added.  The  United  States  standard  for  lemon  extract 
is  5  per  cent  of  lemon  oil  by  volume.  There  are  many 
brands  of  lemon  extract  on  the  market  containing  more 
than  this  amount  of  oil. 

Adulteration  of  lemon  extract.  This  consists  almost  in- 
variably m  the  reduction  of  the  amount  of  lemon  oil  present. 
This  results  from  the  fact  that  the  most  expensive  con- 
stituent of  the  extract  is  the  alcohol.  In  order  to  hold  5 
per  cent  of  lemon  oil  in  solution,  at  least  80  per  cent  of 
alcohol  must  be  present.  In  attempting  to  reduce  the 
amount  of  alcohol  in  the  extract,  the  amount  of  lemon  oil 
held  in  solution  becomes  less  and  less,  until  with  45  per 
cent  of  alcohol  practically  no  oil  at  all  can  be  present. 
Such  an  extract  will,  however,  give  a  very  distinct  odor 
of  lemon,  and  if  colored  yellow  will  find  a  ready  sale.  The 
absence  of  lemon  oil  can  easily  be  shown  by  adding  twice 
the  volume  of  water.  If  the  mixture  remains  clear,  no  oil 
can  be  present.  Extracts  of  standard  strength  give  a  white 
milky  liquid,  due  to  the  particles  of  oil  held  in  suspension. 
The  amount  of  oil  present  is  proportional  to  the  degree  of 
cloudiness  produced.  Methyl  alcohol  has  also  been  used 
instead  of  ethyl  alcohol  in  making  lemon  extract. 

Orange  extract  is  prepared  from  orange  peel  by  a  method 
similar  to  that  used  in  the  preparation  of  lemon  extract. 
It  is  an  alcoholic  solution  of  orange  oil.  It  should  contain 
at  least  5  per  cent  of  orange  oil. 

Almond  extract  is  an  alcoholic  solution  of  the  oil  of 
bitter  almonds,  and  should  contain  at  least  1  per  cent  of 
this  oil.  The  oil  must  first  be  extracted  from  the  almonds 
and  purified  in  order  to  free  it  from  the  poisonous  hydro- 
cyanic acid. 

Other  flavoring  extracts.  Extracts  of  a  number  of  other 
aromatic  vegetables  are  on  the  market,  as  well  as  extracts 


'  FLAVORING  EXTRACTS  187 

of  very  nearly  all  the  common  spices.  Generally  these 
extracts  are  alcoholic  solutions  of  the  oils  which  give  the 
characteristic  flavor  to  the  spices. 

Fruit  flavors.  Attempts  to  extract  the  natural  flavoring 
matter  in  fruits  have  in  most  cases  been  unsuccessful. 
Practically  all  of  the  fruit  essences  on  the  market  are  arti- 
ficial mixtures  of  chemical  compounds,  which  imitate  more 
or  less  closely  the  natural  fruit  flavors.  Several  chemical 
compounds  have  been  prepared,  which  have  an  odor  remark- 
ably similar  to  that  of  some  fruits.  Such  substances  are 
amyl  acetate,  having  an  odor  like  bananas ;  butyric  ether, 
resembling  the  odor  of  pineapples ;  and  amyl  valerianate, 
sometimes  called  apple  oil.  These  substances  are  com- 
pounds of  various  organic  acids,  and  alcohol.  In  other  cases 
where  no  single  substance  has  been  found  the  odor  of 
which  closely  resembles  that  of  the  fruit  to  be  imitated,  a 
mixture  of  several  chemical  substances  is  made  to  imitate 
the  natural  flavor.  If  no  poisonous  substances  are  present, 
and  if  not  sold  as  pure  fruit  flavors,  the  sale  of  such 
artificial  fruit  flavors  is  not  illegal. 


APPENDIX 

CHEMICALS  AND  REAGENTS 

The  amount  of  each  chemical  given  is  in  all  cases  sufficient 
for  the  performance  of  all  the  experiments  given  in  the  test 
for  which  it  is  required.  In  a  good  many  cases  it  is  much  more 
than  necessary  and  would  be  sufficient  for  a  large  class.  It  is 
often  not  economical  to  purchase  chemicals  in  very  small  quan- 
tities. All  chemicals  in  this  list,  as  well  as  the  apparatus  given 
in  the  following  list,  may  be  purchased  of  Eimer  «&  Amend, 
Third  Avenue  and  18th  Street,  New  York. 

Acetic  acid  (^  lb.).  The  strongest  commercial  quality  of  this 
acid  is  known  as  glacial  acetic  acid  and  is  very  nearly  100  per  cent 
pure.  Dilute  acetic  acid  is  prepared  by  adding  40  ccm.  of  the  gla- 
cial acid  to  100  ccm.  of  water.   This  strength  is  commonly  used. 

Agar-agar.  This  is  a  dried  seaweed  which  has  the  property  of 
absorbing  a  large  amount  of  water  and  solidifying  into  a  jelly. 

Ammonia  (1  lb.).  The  concentrated  c.p.  solution  as  purchased 
must  be  diluted  with  2  volumes  of  water  for  ordinary  use.  It 
should  be  kept  in  a  glass-stoppered  bottle.  If  acid  of  any  kind  is 
accidentally  spilled  on  clothing,  ammonia  should  be  applied. 

Ammonium  molybdate  (1  oz.).  A  white  crystalline  salt  used 
in  nitric  acid  solution  as  a  test  for  phosphoric  acid,  which  pro- 
duces a  yellow,  finely  divided  precipitate.  The  solution  is  pre- 
pared as  follows:  7^  gm.  of  ammonium  molybdate  are  dissolved 
in  50  ccm.  of  water  with  the  addition  of  a  little  ammonia  if 
necessary.  This  solution  is  poured  with  constant  stirring  into 
a  mixture  of  25  ccm.  of  concentrated  nitric  acid  and  25  ccm.  of 
water.  The  solution  is  placed  in  a  glass-stoppered  bottle  and 
allowed  to  stand  for  several  days.  The  clear  liquid  is  added  to 
the  solution  to  be  tested  for  phosphoric  acid. 

189 


190  PURE  FOODS 

Amyl  alcohol  (^  lb.).    A  colorless  liquid. 

Barium  chloride  (1  oz.).  White  crystals.  A  solution  is  pre- 
pared by  dissolving  1  oz.  in  200  ccm.  of  water. 

Borax  (1  oz.).   A  white  powder. 

Bromine  (1  oz.).  A  dark  red,  fuming,  highly  corrosive  liquid. 
Great  care  should  be  taken  not  to  allow  liquid  bromine  to  come 
in  contact  with  the  skin  nor  to  breathe  the  fumes.  A  few  drops 
are  placed  in  a  glass-stoppered  bottle,  which  is  filled  with  dis- 
tilled water  and  well  shaken.  This  saturated  solution  is  called 
bromine  water. 

Carbon  disulphide  (|  lb.).    A  heavy  volatile  liquid. 

Caustic  soda  (i  lb.).  A  white  solid  usually  sold  in  sticks. 
Both  the  solid  caustic  and  the  solution  should  be  kept  well 
stoppered,  as  the  carbon  dioxide  of  the  air  converts  it  into 
sodium  carbonate.  The  caustic  soda  solution  is  prepared  by 
dissolving  20  gm.  in  100  ccm.  of  water. 

Ether  (i  lb.).  A  very  volatile,  highly  inflammable  liquid.  The 
vapor  forms  an  explosive  mixture  with  the  air.  It  should  be 
kept  in  a  bottle  stoppered  with  a  well-fitting  cork,  preferably 
in  a  cool  place.  It  should  never  be  handled  near  a  flame  of 
any  kind. 

Fehling's  solution.  This  is  an  alkaline  solution  of  copper, 
which  is  used  to  test  for  reducing  sugars,  such  as  dextrose, 
levulose,  etc.  When  the  solution  is  boiled  with  such  sugars, 
the  copper  is  reduced  to  the  cuprous  condition,  which  is  indi- 
cated by  the  change  from  a  blue  transparent  solution  to  a 
bright  red  precipitate.  The  solution  is  prepared  immediately 
before  it  is  used  by  mixing  equal  portions  of  two  solutions 
A  and  B,  which  are  prepared  as  follows : 

A.  Dissolve  7  gm.  (about  |  oz.)  of  crystallized  sulphate  of 
copper  in  100  ccm.  of  water. 

B.  Dissolve  34.6  gm.  of  crystallized  Rochelle  salt  in  45  ccm. 
of  water,  also  25  gm.  of  caustic  soda  in  40  ccm.  of  water.  Mix 
these  two  solutions  and  dilute  to  100  ccm. 

Ferric  chloride  (1  oz.).  A  red  solid  easily  soluble  in  water.  The 
solution  is  prepared  by  dissolving  5^  gm.  in  100  ccm.  of  water. 


APPENDIX  191 

Ferrous  sulphate  (1  oz.).  A  green  crystalline  salt.  As  it  is 
not  stable  in  solution,  a  few  crystals  are  dissolved  in  water 
when  needed. 

Gelatin  (gold  label). 

Hydrochloric  acid  (also  known  commercially  as  muriatic  acid) 
(1  lb.).  The  acid  as  purchased  is  a  solution  in  water  of  the 
pure  acid,  which  is  a  gas.  The  strongest  acid  sold  contains 
about  40  per  cent  of  acid.  This  solution  is  a  fuming  corrosive 
liquid.  If  spilled  on  the  hands,  it  is  washed  off  with  water. 
If  spilled  on  the  clothing,  it  should  be  neutralized  with  am- 
monia and  then  washed  out  with  water. 

A  dilute  solution  for  ordinary  use  is  prepared  by  mixing 
5  volumes  of  the  strong  acid  with  8  volumes  of  water. 

Iodine  (1  oz.).  A  gray-black  crystalline  solid,  which  slowly 
volatilizes  at  ordinary  temperatures.  It  acts  on  the  skin  and 
most  organic  matter.  It  is  readily  absorbed  by  ammonia.  It 
is  soluble  in  alcohol  and  a  water  solution  of  potassium  iodide. 
The  potassium  iodide  solution  gives  a  blue  color  with  starch. 
It  is  prepared  as  follows :  2  gm.  of  iodine  are  agitated  with  a 
solution  of  6  gm.  of  potassium  iodide  in  a  few  cubic  centi- 
meters of  water.  When  the  iodine  is  entirely  dissolved,  the 
solution  is  diluted  with  water  until  its  volume  is  100  ccm.  It 
should  be  kept  in  a  glass-stoppered  bottle. 

Lead  acetate  (1  oz.).  A  white  crystalline  solid.  By  heating  a 
water  solution  with  lead  oxide  basic  lead  acetate  is  produced, 
which  is  used  to  precipitate  fruit  juices  and  other  soluble 
organic  matter.  The  solution  is  prepared  as  follows :  18  gm. 
of  lead  acetate  are  dissolved  in  70  ccm.  of  hot  distilled  water 
and  11  gm.  of  lead  oxide  added.  The  mixture  is  boiled  for 
half  an  hour  with  occasional  stirring,  after  which  it  is  allowed 
to  settle  for  a  few  minutes  and  the  clear  solution  poured  off  or 
filtered.  Enough  distilled  water  is  added  to  make  the  volume 
about  81  ccm.  The  solution  must  be  kept  in  well-stoppered 
bottles.  A  dilute  solution  made  by  adding  about  4  volumes 
of  water  to  1  volume  of  the  strong  solution  is  suitable  for 
ordinary  use. 


192  PUEE  FOODS 

Lead  oxide  (1  oz.).    A  heavy  yellow  to  orange  powder. 

Limewater.  A  saturated  water  solution  of  calcium  oxide. 
It  is  prepared  by  treating  a  few  ounces  of  ordinary  lime  with 
water,  shaking  thoroughly,  and  allowing  to  stand  until  the  in- 
soluble matter  has  settled.  The  clear  liquid  is  siphoned  off  or 
decanted  into  a  bottle,  which  should  be  kept  well  stoppered. 

Litmus  paper.  A  sheet  each  of  blue  and  red  should  be  pur- 
chased and  cut  into  strips  of  convenient  size.  The  paper  is 
used  to  test  for  acids  and  alkalies.  Acids  turn  the  blue  paper 
red,  while  alkalies  or  bases  turn  the  red  paper  blue. 

Magnesium  (^  oz.).  A  white  metal  which  is  sold  in  the  form 
of  narrow  ribbons. 

Methyl  alcohol  (1  pt.).  Also  known  as  wood  alcohol.  A  vola- 
tile combustible  liquid. 

Methyl  orange  (1  oz.).  A  yellow  powder  soluble  in  water  and 
used  as  an  indicator  for  acids  and  bases.  Acids  give  a  red  color 
to  the  solution,  while  alkalies  give  a  yellow  color.  The  solution 
is  prepared  by  dissolving  1  gm.  in  1000  ccm.  of  distilled  water. 

Nitric  acid  (1  oz.).  The  pure  acid  is  a  fuming,  corrosive  liquid, 
generally  colored  reddish  on  account  of  the  presence  of  nitrous 
acid.  It  acts  rapidly  on  wood,  cloth,  the  skin,  and  most  organic 
matter.  The  ordinary  concentrated  acid  contains  about  one 
third  its  weight  of  water.  For  many  purposes  a  dilute  acid 
is  prepared  by  adding  2  volumes  of  water  to  1  volume  of  the 
concentrated  acid. 

Phenolphthalein  (1  oz.).  A  white  crystalline  solid  used  in 
alcoholic  solution  as  an  indicator  for  acids  and  bases.  In  acid 
solution  the  indicator  is  colorless,  while  alkalies  give  a  deep 
red  color.  The  solution  is  prepared  by  dissolving  j\  gm.  in 
100  ccm.  of  alcohol. 

Phosphoric  acid  (1  lb.).  In  its  most  concentrated  form  (glacial 
phosphoric  acid)  this  acid  is  a  thick  sirupy  liquid.  For  ordi- 
nary use  a  dilute  solution,  prepared  by  adding  3  volumes  of 
water,  is  sufficiently  concentrated. 

Resorcin  (1  oz.).  This  organic  compound  is  used  in  testing  for 
tartaric  acid.    One  gram  is  dissolved  in  50  gm.  of  concentrated 


APPENDIX  193 

sulphuric  acid.  When  heated  with  even  a  very  small  quantity 
of  tartaric  acid  this  solution  gives  a  beautiful  wine  color. 

Rochelle  salt  (2  oz.).  This  is  the  sodium  and  potassium  salt 
of  tartaric  acid.  It  has  the  property  of  holding  copper  in 
solution  in  the  presence  of  an  alkali,  and  is  therefore  used  in 
Fehling's  solution. 

Silver  nitrate  (1  oz.).  A  white  crystalline  salt,  very  soluble 
in  water.  A  solution  of  convenient  strength  may  be  prepared 
by  dissolving  3^  gm.  of  the  salt  in  100  ccm.  of  water.  The 
solution  should  be  kept  in  a  glass-stoppered  bottle  made  of 
dark-brown  glass  ;  or,  if  this  is  not  at  hand,  the  solution  should 
be  protected  from  the  light  by  pasting  dark  paper  around  the 
bottle. 

Sodium  (metallic)  (1  oz.).  In  the  pure  state  this  element  is  a 
soft  silvery-white  metal.  It  oxidizes  very  rapidly  in  the  air 
and  reacts  violently  with  water.  It  is  therefore  sold  in  sealed 
tin  cans,  and  must  be  kept  under  kerosene  or  other  mineral  oil. 
The  oil  can  be  removed  from  the  sodium  by  means  of  dry  filter 
paper.  The  metal  can  easily  be  cut  with  a  clean  dry  knife.  It 
should  not  be  left  exposed  to  the  air  or  moisture  for  any  length 
of  time. 

Sodium  carbonate  (dry)  (1  lb.).  A  white  powder,  very  soluble 
in  w^ater,  composed  of  sodium  and  carbonic  acid.  Its  solution 
is  strongly,  alkaline  and  neutralizes  acids. 

Sodium  acid  sulphite  (^  lb.).  A  white  salt,  very  soluble  in 
water,  composed  of  sodium  and  sulphurous  acid.  It  is  largely 
used  as  a  preservative. 

Starch  iodate  paper.  Starch  paste  is  prepared  as  directed  on 
page  15.  A  small  quantity  of  potassium  iodate  is  dissolved  in 
water  and  added  to  the  starch  paste.  Strips  of  filter  paper  are 
dipped  into  the  mixture  and  hung  up  to  dry.  Sulphur  dioxide 
(fumes  of  burning  sulphur)  or  sulphurous  acid  turns  the  paper 
dark  blue  and  then  bleaches  it. 

Sulphur  (1  oz.).  A  yellow  solid  found  on  the  market  in  rolls 
or  as  a  powder  (flowers  of  sulphur).  Eoll  sulphur  is  the  form 
most  soluble  in  carbon  disulphide. 


194  PUEE  FOODS 

Sulphuric  acid  (1  lb.).  In  the  pure  state  this  acid  is  a  thick, 
heavy,  viscous  liquid.  It  chars  paper,  wood,  and  most  organic 
matter  and  reacts  violently  with  water.  If  spilled  on  the  cloth- 
ing, ammonia  should  be  applied ;  if  on  the  skin,  it  should  be 
immediately  washed  off  with  cold  water.  For  ordinary  use 
dilute  acid  should  be  prepared  by  diluting  1  volume  of  the 
concentrated  acid  with  6  volumes  of  distilled  water.  The  water 
must  not  be  poured  into  the  acid,  because  the  large  amount  of 
heat  developed  is  liable  to  produce  violent  boiling  and  spatter- 
ing of  the  acid.  When  it  is  poured  slowly  and  with  constant 
stirring  into  the  water,  no  violent  action  takes  place.  Both  the 
concentrated  and  dilute  acid  should  be  kept  in  glass-stoppered 
bottles. 

Turmeric  paper.  This  paper  may  be  purchased  or  it  may  be 
prepared  by  dipping  strips  of  filter  paper  into  an  alcoholic 
solution  of  turmeric  and  allowing  them  to  dry.  Alkalies  turn  the 
paper  red.  It  is  most  largely  used  to  detect  boric  acid.  When 
dipped  into  a  solution  of  this  acid  to  which  hydrochloric  acid 
has  been  added,  and  then  dried,  a  bright  red  color  is  produced, 
which  is  turned  green  by  alkalies.  The  paper  must  not  be  dried 
at  a  temperature  above  100°  C.  or  that  of  boiling  water. 

Witte's  peptone  (^  lb.).  A  white  powder  used  in  the  prepara- 
tion of  nutrient  gelatin. 

Wood  alcohol  (1  lb.).  Also  called  methyl  alcohol.  A  colorless, 
volatile  liquid  obtained  by  dry  distillation  of  wood. 

APPARATUS 

The  following  list  includes  all  the  apparatus  necessary  to 
prepare  most  of  the  experiments  given  in  the  text.  The  more 
expensive  apparatus  which  would  be  required  in  order  to  per- 
form a  few  of  the  most  difficult  experiments  is  given  in  a 
separate  list. 

Air  oven.  This  piece  of  apparatus  consists  of  a  copper  oven 
which  can  be  heated  with  a  Bunsen  burner.  A  suitable  open- 
ing in  the  top  is  provided  for  the  insertion  of  a  thermometer, 
so  that  the  temperature  can  be  regulated  to  suit  the  substance 


APPENDIX  195 

to  be  heated  or  dried  in  the  oven.  For  many  purposes  an 
ordinary  gas  oven  is  entirely  satisfactory. 

Beakers.  Thin  glass  vessels  in  which  liquids  may  be  boiled. 
They  may  be  obtained  in  a  great  variety  of  sizes.  For  ordinary 
use,  nests  of  beakers  having  capacities  of  2,  4,  6,  8, 10,  and  12  oz. 
are  satisfactory. 

Bottles.  One  and  one-half  dozen  glass-stoppered  bottles  of 
250  ccm.  capacity. 

Bunsen  burner.  In  the  absence  of  a  suitable  stove,  Bunsen 
burners  are  convenient.  They  are  attached  to  gas  jets  by 
means  of  rubber  tubing. 

Filter  paper.  Circular  paper  may  be  obtained  in  packages 
of  100  sheets  of  various  sizes.  Paper  of  12  l  or  15  cm.  in 
diameter  is  convenient. 

Flasks.  The  so-called  Florence  flasks  are  flat-bottomed  and 
suitable  for  most  purposes.    A  convenient  size  is  8  oz. 

Funnels  are  used  for  holding  the  paper  when  Altering.  Size 
3  to  4  in. 

Graduates  are  tall  vessels  on  which  the  capacity  in  cubic 
centimeters  is  marked,  and  are  used  for  measuring  liquids. 
Size  100  ccm. 

Pipestem  triangles  are  wire  triangles  covered  with  clay  tubing, 
and  are  used  for  holding  vessels  while  being  heated  with  the 
Bunsen  burner.    Size  3  to  4  in. 

Platinum  wire  (1  ft.).  This  metal  resists  the  action  of  most 
chemical  reagents  and  cannot  be  melted  or  oxydized  in  the  gas 
flame.  The  wire  is  used  for  inserting  drops  of  solutions  to  be 
tested  in  the  flame  of  the  Bunsen  burner.    Size  No.  25. 

Porcelain  dish.  These  dishes  are  suitable  for  evaporating 
liquids,  and  may  be  subjected  to  the  full  heat  of  the  gas  flame. 
Size  3  in. 

Porcelain  mortar.  Suitable  for  grinding  or  mixing  chemicals. 
Size  3  in. 

Test  tube  (^  gross).  Suitable  for  a  great  variety  of  tests  on 
small  quantities  of  liquid.  They  may  be  heated  in  the  Bunsen- 
burner  flame.    Size  6  in. 


196  PUEE  FOODS 

Thermometers.  Chemical  thermometers  have  the  scale  etched 
on  the  glass  tube  and  are  made  entirely  of  glass.    360°  C. 

Tripod  (2).  An  iron  stand  suitable  for  the  support  of  beakers 
or  other  vessels  which  must  be  heated  with  the  Bunsen  burner. 
A  wire  gauze  should  be  placed  on  the  tripod  in  order  to  dis- 
tribute the  heat  of  the  Bunsen  burner  and  to  serve  as  a  support 
for  the  beaker. 

Water  bath.  A  copper  or  iron  vessel  suitable  for  boiling 
water,  and  fitted  with  a  lid  composed  of  rings  so  that  vessels 
of  various  sizes  may  be  heated  by  the  steam.  As  the  tempera- 
ture of  the  steam  is  100°  C,  the  vessel  heated  or  its  contents 
cannot  rise  above  this  temperature. 

Wire  gauze  (^  doz.).  Four-inch  squares  of  iron  or  copper  are 
suitable  for  most  purposes.  Wire  gauze  transmits  the  heat  of 
a  gas  flame,  spreading  it  over  a  large  surface  and  protecting 
the  vessel  heated  from  direct  contact  with  the  flame. 

SPECIAL  APPARATUS  REQUIRED  FOR  SOME  OF  THE 
MORE  DIFFICULT  EXPERIMENTS 

Balance.  The  ordinary  analytical  chemical  balance  is  a  very 
delicate  instrument,  and,  with  a  set  of  weights,  can  be  purchased 
for  from  $50  to  |150.  Fairly  satisfactory  results  could  be 
obtained  with  a  cheaper  instrument,  which  would  be  some- 
what less  sensitive. 

Burette  (2).  An  instrument  consisting  of  a  glass  tube  grad- 
uated to  tenths  of  cubic  centimeters  and  having  a  stopcock 
attached,  so  that  any  desired  quantity  of  liquid  may  be  de- 
livered.   The  usual  capacity  is  50  ccm. 

Casserole.  A  cup-shaped  porcelain  vessel  provided  with  a 
handle  and  suitable  for  heating  liquids,  especially  when  it  is 
desirable  to  keep  the  liquid  agitated.  A  very  convenient  size 
is  250  ccm. 

Petri  dish  (1  doz.).  These  are  flat,  circular  glass  dishes  pro- 
vided with  glass  covers.  They  are  used  for  making  bacterial 
cultures  and  counts. 


APPENDIX  197 

Pipettes.  Glass  tubes  having  a  bulb  at  the  center  and  marked 
to  deliver  a  definite  quantity  of  liquid,  such  as  1  ccm.,  5  ccm., 
10  ccm.,  25  ccm.,  etc.  For  bacteriological  work  1-ccm.  pipettes 
are  used,  two  dozen  being  a  suitable  quantity.  Half  a  dozen  pi- 
pettes graduated  so  as  to  deliver  either  9  or  10  ccm.  would  also 
be  required.  These  pipettes  must  be  sterilized  and  kept  in  a 
sterilized  receptacle  until  used.  For  this  purpose  tin  or  copper 
cans  of  suitable  size,  provided  with  a  lid  or  long  test  tubes, 
must  be  employed.  The  latter  may  be  closed  with  a  plug  of 
cotton. 

Platinum.  This  metal  is  eminently  suited  for  chemical  work 
because  it  is  unaffected  by  most  chemical  reagents,  and  can  be 
heated  to  the  highest  temperature  obtained  with  the  gas  flame 
without  injury.  In  making  food  tests  platinum  dishes  about  3 
in.  in  diameter  are  very  useful  for  burning  the  organic  matter  of 
foods.  Tests  on  smaller  quantities  can  be  carried  out  on  plati- 
num foil,  which  can  also  be  used  for  the  deposition  of  copper, 
for  which  purpose  platinum  dishes  are  also  well  adapted. 


INDEX 


Acetic  acid,  189 

Acid,  stearic,  preparation  of,  69 
Acidity,  of  oils,  determination  of, 
68 
testing  fruit  juices  for,  152 
titration  of,  56 
Acids,  fatty,  63 

found  in  fats  and  oils,  62,  63 
found  in  fruits,  143 
Adulterated  foods,  18,  22 
Adulterated  jams,  151 
Adulteration,  of  bread,  163 
of  cake,  163 
of  chocolate,  116 
'  of  cocoa,  112 

of  lemon  extract,  186 
of  spices,  177 
i  of  vegetables,  155 

i         Agar-agar,  189 

nutrient,  preparation  of,  59 
Air  oven,  194 
Alcohol,  use  of,  as  a  preservative, 

132 
Allspice,  173 
Almond  extract,  186 
Alum,  163 

baking  powder,  167 

baking  powders,  objections  to 

use  of,  168 
testing  baking  powders  for,  169 
Aluminium,  testing  baking  powders 

for,  170 
Ammonia,  189 
Ammonium  molybdate,  189 


Amyl  acetate,  144,  187 

Amyl  alcohol,  190 

Amyl  valerianate,  144,  187 

Aniline  dye,  experiments  with  a 

poisonous,  125 
Aniline  dyes,  123 

and  other  food  colors,  122 

arsenic  in,  124 

methods  of  proving  harmless, 
124,  125 

permitted  by  United  States  De- 
partment of  Agriculture,  126 

poisonous,  20,  123 

testing  for,  154,  158 
Apparatus,  194 
Appendix,  189 
Apples,  composition  of,  142 
Argols,  143 

Arsenic  in  food  colors,  124 
Artificial  extracts,  184 
Artificial  jellies,  150 

wholesomeness  of,  151 
Ash  in  foods,  definition  of,  5 

test  for,  16 
Atwater-Mahler     bomb     calorim- 
eter, 9 

Bacteria,  action  of,  on  milk,  45 

action  of  preservatives  toward, 
137 

count  of,  57 

danger  of  consuming  large  num- 
bers of,  137 

determination  of  number  of,  54 


199 


200 


PURE  FOODS 


Bacteria,  food  of,  44 

in  milk,  43,  45 

in  milk  sold  in  New  York  City,  53 

plate  cultures  of,  58 
Bacteria  content   of   milk,   varia- 
tions in,  53 
Baking  powder,  alum,  167 

cream  of  tartar,  167 

phosphate,  167 
Baking  powders,  testing  for  alum, 
169 

testing  for  phosphates,  170 

testing  for  tartaric  acid,  171 
Balance,  196 
Balanced  diet,  23 
Banana  oil,  144 
Barium  chloride,  190 
Barley  flour,  162 
Barn,  old-style,  45 
Beakers,  195 
Beets,  manufacture  of  sugar  from, 

98 
Benzoate  of  soda,  139 

harmless,  136 
Benzoic  acid,  83 
Bleached  flour,  161 
Bomb  calorimeter,  9 
Bombay  mace,  176 
Borax,  136 

test  for,  in  milk,  40 

testing  for,  in  meat,  85 
Boric  acid,  83,  136  _ 
Bread,  159 

adulteration  of,  163 

butter,  and  milk,  daily  ration  of, 
36 

Liebig's  method  of  raising,  166 

raised  by  carbon  dioxide  gas,  166 

raising  of,  162 

sour,  166 

water  in,  163 


Breakfast  cocoas,  110 

composition  of,  112 
Breakfast  foods,  164 
Bromine,  190 
Buckwheat  flour,  162 
Buddeized  milk,  52 
Bunsen  burner,  195 
Bur  mills,  91 
Burette,  196 
Butter,  71 

composition  of,  71 

constituents  of,  72 

flavor  of,  73 

foam  test  for,  76 

milk  test  for,  76 

process,  73 

production  of,  71 

renovated,  73 
Butter  fat,  72 

composition  of,  72 
Butterine,  74 
Buttermilk,  39 
Butyric  ether,  187 

Caffeine,  112 

Cake,  adulteration  of,  163 
Calculation  of  calorific  value,  10 
Calorie,  a  measure  of  the  energy 
of  food,  7 
definition  of,  8 
Calorific  value,  calculation  of,  10 
Calorimeter,  description  of,  8 
Candies,  101 

Candy,  amount  of  dyes  in,  126 
and  nuts,  adult  ration  of,  102 
detection  of  glucose  in,  121 
flavoring  matter  for,  121 
food  value  of,  101 
not  a  sustaining  food,  103 
sugars  present  in,  103 
use  of  coloring  matter  in,  118 


INDEX 


201 


Candy,  use  of  eggs  in,  118 

use  of  gelatin  in,  118 

use  of  sulphurous  acid  in,  104 
Cane  sugar,  3 

manufacture  of,  98 

refining  of,  98 
Canned  fruits,  148 
Canned  vegetables,  155 

testing  for  copper  sulphate,  157 

testing  for  sulphur  dioxide,  157 
Carbohydrates,  88 

calorific  value  of,  10 

definition  of,  2 

importance  of,  in  the  diet,  88 

solubility  of,  3 
Carbon  dioxide  gas,  used  for  rais- 
ing bread,  166 
Casein,  34,  40 
Casserole,  196 
Cassia,  173 
Catsup,  139,  157 
Caustic  soda,  190 

normal  solution  of,  56 
Cayenne,  composition  of,  174 
Cayenne  pepper,  174 
Cellulose,  2,  3 
Centrifuge,  99 
Cereals,  159 
Certified  milk,  48 
Charcoal  filters,  93,  94 
Chemical  composition  of  fats,  61 
Chemical  preservatives,  classed  as 
drugs,  135 

digestion  experiments  on,  136 

efficiency  of,  133 

for  meats,  83 

tasteless,  133 
Chemicals,  189 
Chicago  stockyards,  79 
Children,    influence   of   the    milk 
supply  on  the  death  rate  of,  53 


Children,  rations  for,  25 
Chlorophyll,  141 
Chocolate,  101,  114 

adulteration  of,  116 

composition  of,  114 

cooling  room  for,  120 

production  of,  by  grinding  cocoa 
beans,  115 
Chocolate  creams,  102,  116 

food  value  of,  101,  106 
Cinnamon,  173 

flavor  of,  174 
Citric  acid,  144 

Cleanliness  vs.  preservatives,  138 
Cloves,  174 

composition  of,  174 
Cocoa,  101 

adulteration  of,  112 

breakfast,  110 

composition  of  breakfast,  112 

fruit  of,  gathering,  107 

history  of,  106 

hulls  of,  108 

manufacture  of,  113 

Mexican,  origin  of,  106 

nutritive  value  of,  112 

stimulating  properties  of,  112 
Cocoa  beans,  drying  in  the  sun, 
109 

grinding  into  chocolate,  115 

roasting  of,  107 

roasting  and  hulling.  111 
Cocoa  butter,  108 
Cocoa  nibs,  108 
Cocoa  tree,  106 
Coconut  oil,  64 
Coefficient  of  digestibility,  26 
Cold  storage,  130 

length  of,  131 

of  fruits,  147 

of  meat,  82 


202 


PURE  FOODS 


Coloring  matter  in  candy,  118 
Common  salt  as  a  preservative,  132 
Comparative  cost,  of  foods,  29 

of  milk,  cream,  and  butter,  38 
Composition,  of  foods,  1,  11 

of  milk,  35 
Concentration  of  sirup,  96 
Condimental  foods,  172 
Condiments,  origin  of,  172 
Constituents  of  milk,  34 
Conversion   of    starch   into   sirup 

and  sugar,  92 
Converters,  92 
Cooling  room,  120 
Copper,  as  coloring  matter  in  vege- 
tables, 156 
Copper  sulphate  in  vegetables,  test- 
ing for,  157 
Corn,   amount  used  in  producing 
corn  products,  98 

manufacture  of  starch  from,.  90 

storage  of,  89 

structure  of  a  grain  of,  90 
Com  oil,  production  of,  91 
Com  sirup,  amount  consumed  in 
the  United  States,  98 

composition  of,  96 
Cost,  of  a  daily  ration  of  a  single 
food,  29     . 

of  a  day's  food  of  various  arti- 
cles, 30-32 

of  food,  23 

of  milk,  cream,  and  butter,  38 
Cottolene,  66 
Cottonseed  oil,  64 

consumption  of,  65 

test  for,  70 
Count  of  bacteria,  57 
Cream,  38 

comparative  cost  of,  38 
Cream  of  tartar,  143 


Cream  of  tartar  baking  powders, 

167 
Cream-casting  room,  119 

Daily  ration,  23 

of  bread,  butter,  and  milk,  36 
of  milk,  36 
Day's  food  of  various  articles,  cost 

of,  30-32 
Death  rate  of  children,  influence 

of  the  milk  supply  on,  54 
Deception  in  foods,  21 
Desiccated  fruits,  147 
Desiccated  vegetables,  156 
Dextrine,  3,  92,  103 
Dextrose,  3,  103 

production  of,  93,  96 
Diastase,  action  of,  on  starch,  100 
Diet,  balanced,  23 
function  of  sugar  in,  101 
importance  of  carbohydrates  in, 

88 
importance  of  fats  in,  60 
importance  of  meat  in,  78 
importance  of  spices  in,  172 
Digestibility,  coefficient  of,  26 
Digestion,  experiments  w^ith  chem- 
ical preservatives,  136 
of  protein,  16 
of  starch,  88,  100 
stimulated  by  attractive  foods, 
172 
Diphtheria    and     other    diseases 

transmitted    by   milk,    46 
Drugs,      chemical      preservatives 

classed  as,  135 
Drying,  preservation  by,  129 

sanitary  conditions  during,  130 
Dye,  amount  used  in  food,  126 
experiments  with  a  poisonous, 
125 


INDEX 


203 


Dyes,  aniline,  122 

harmless  vegetable,  126 
methods  of  proving  harmless,  124 
permitted  by  United  States  De- 
partment of  Agriculture,  126 
testing  for,  154 

Egg  substitute,  122, 164 
Eggs,  163 

dried,  118 

preservation  of,  138 

preserved,  118 

use  of,  in  candy,  118 
Energy,  method  of  measuring,  7 

obtained  from  food,  6 
Enzymes,  100 
Ether,  190 
Ethyl  acetate,  144 
Evaporated  milk,  39 
Excessive  consumption  of  protein, 

26 
Exhausted  spices,  178 
Experiments  with  a  poisonous  dye, 

125 
Extract,  almond,  186 

lemon,  184,  186 

orange,  186 
Extracts,  artificial,  184 

flavoring,  180 

Fat,  percentage  of,  in  New  York 
City  milk,  37 

Fats,  and  oils,  4,  60 
acids  in,  4,  63 
calorific  value  of,  10 
chemical  composition  of,  61 
decomposition  of,  62 
digestion  of,  4 
glycerin  and  acids  in,  62 
in  the  diet,  importance  of,  60 
percentage  of,  in  foods,  60 


Fats,  and  oils,  rancidity  of,  4 
Fatty  acids,  63 

test  for,  15 
Fehling's  solution,  190 

use  of,  in  testing  for  sugar,  15 
Ferric  chloride,  190 
Ferrous  sulphate,  191 
Filter  paper,  195 
Filters,  charcoal,  93,  94 
Flasks,  195 
Flavor,  of  fruits,  144 

of  oils,  64 
Flavoring  extracts,  180 

utility  of,  180 
Flavoring  matter  for  candy,  121 
Flour,  barley,  162 

bleached,  161 

buckwheat,  162 

grades  of,  160 

Graham,  160 

Indian  corn,  162 

mixed,  161 

patent,  160 

rye,  162 

whole-wheat,  160 
Foam  test  for  butter,  76 
Food,  adulterated,  22 

amount  consumed,  6 

amount  of  dyes  used  in,  126 

an  ideal,  34 

as  a  source  of  energy,  6 

bread  an  ideal,  159 

cost  of,  23 

definition  of,  6,  7 

function  of,  in  the  human  sys- 
tem, 6 

functions  of,  7 

importance  of  milk  as,  33 

method  of  measuring  the  energy 
of,  7 

necessity  of  chewing,  100 


204 


PUKE  FOODS 


Food,  oxidation  of,  in  the  human 
system,  6 

pure,  definition  of,  18 

staple,  36 
Food  colors,  122 

aniline,  123 

harmless,  122 

vegetable,  123 
Food  oils,  68 
Food  value,  of  candy,  101 

of  chocolate  creams,  106 

of  fruits,  146 

of  jams  and  jellies,  149 

reduction  of,  21 
Foods,  adulterated,  18 

classes  of,  2 

comparative  cost  of,  29 

composition  of,  1,  11 

condimental,  172 

deception  in,  21 

decomposed,  preservation  of,  138 

fraudulent  coloring  of,  122 

importance  of  analysis  of,  4 

interchangeable,  24 

legal  standards  of,  22 

long-used,  pure,  19 

misleading  labels  of,  21 

not  sterilized  by  preservatives,  139 

percentage  of  fats  in,  60 

poisonous  constituents  of,  20 

preservation  of,  127 

substitution  of,  19 
Foose  mills,  90 
Formaldehyde^,  138 

test  for,  in  milk,  41 
Fruit  flavors,  187 
Fruit  juices,  testing  for,  153 

testing  for  acidity  of,  152 
Fruits,  141 

acids  found  in,  143 

canned,  148 


Fruits,  cold  storage  of,  147 

composition  of,  141,  145 

desiccated,  147 

dried,  147 

flavor  of,  144 

food  values  of,  146 

fresh,  good  summer  diet,  146 

mineral  matter  in,  144 

preserved,  good  winter  diet,  146 

ripening  of,  141 

testing  for  pectin,  152 

testing  for  starch,  152 
Fuchsin,  125 
Fuller's  earth,  66 
Funnels,  195 

Gelatin,  118 

manufacture  of,  84 

nutrient,  preparation  of,  55 
Germ  separators,  90 
Germs  of  corn,  separation  of,  90 
Ginger,  175 

black,  175 

white,  175 
Glucose,  96 

composition  of,  96,  103 

detection  of,  121 

food  value  of,  101 

nutritive  value  of,  97 

production  of,  from  starch,  92 
Gluten,  159 

composition  of,  90 
Glycerin  and  acids  in  fats,  62 
Graduates,  195 
Graham  flour,  160 
Grinding  nutmegs,  178 
Gypsum,  163 

Harmless  dye,  experiments  with, 

125 
Hazelnut  oil,  68 


INDEX 


205 


Hesse,  Dr.  Bernhard  C,  126 
Holt,  Dr.  Emmett,  54 
Honey,  96 

Human  beings,  action  of  preserv- 
atives on,  136 
Hydrochloric  acid,  191 
Hydrogen  peroxide,  139 

Indian  corn  flour,  162 
Inspected  meat,  80 
Interchangeable  foods,  24 
Iodine,  191 

Iodine  test  for  starch,  15 
Iron  oxide,  116 

Jams,  141,  148 

adulterated,  151 

composition  of,  148 

food  value  of,  149 

testing  for  dyes,  154 
Jellies,  141,  148 

artificial,  150 

composition  of,  149 

food  value  of,  149 

testing  for  dyes,  154 

wholesomeness  of  artificial,  151 
Jelly  making,  149 

Lard  substitutes,  66 
Lead  acetate,  191 
Leavening  agents,  165 
Lees,  143 

Legal  standards  of  foods,  22 
Lemon  extract,  184 

adulteration  of,  186 
Levulose,  3,  96,  104 
Liebig's  method  of  raising  bread,  166 
Lime  water,  192 
Linters,  65 
Litmus  paper,  192 
Long-used  foods,  pure,  19 


Mace,  176 
Magnesium,  192 
Malt,  100 
Maltine,  100 
Maltose,  4,  96 

production  of,  from  starch,  93 
Meat,  characteristics  of  sound,  81 

cold  storage  of,  82 

danger  of  excessive  use  of,  79 

diseased,  characteristics  of,  81 

importance  of,  in  the  diet,  78 

inspected,  80 

preservation  of,  138 

refrigeration  of,  81 

similarity  of  various  kinds  of ,  81 

substitutes  for,  78 

testing  for  borax  in,  85 

testing  for  sulphites  in,  85 

unsanitary,  80 
Meats,  78 

chemical  preservatives  for,  83 
Methyl  alcohol,  192 
Methyl  orange,  192 
Microscopic  examination  of  spices, 

179 
Milk,  33 

a  staple  food,  36 

action  of  bacteria  on,  45 

amount  consumed  in  New  York 
City,  33 

bacteria  in,  43,  45 

bacteria  transmitted  by,  46 

Buddeized,  52 

certified,  48 

comparative  cost  of,  38 

composition  of,  35 

constituents  of,  34,  40 

cream  and  butter,  comparative 
cost  of,  38 

daily  ration  of,  36 

determination  of  bacteria  in,  54 


20d 


PUEE  FOODS 


Milk,  diphtheria  and  other  diseases 
transmitted  by,  46 

evaporated,  39 

high  protein  content  of,  35 

importance  of,  as  food,  33 

modified,  35 

nutritive  vahie  of,  36 

Pasteurized,  50 

preservatives  in,  49 

pure,  production  of,  47 

scarlet  fever  transmitted  by,  46 

skim,  39 

sold  in  New  York  City,  bacteria 
in,  53 

sterilized,  49 

supply,   influence   of,  on   death 
rate  of  children,  54 

test  for  borax  in,  40 

test  for  formaldehyde  in,  41 

typhoid  fever  transmitted  by,  46 

variations  in  composition  of,  37 

variations  in  bacteria  content  of, 
53 
Milk  sugar,  40 
Milk  test  for  butter,  76 
Mineral  matter,  and  solids  of  milk, 
test  for,  16 

definition  of,  2 

digestion  of,  5 

in  foods,  5 

in  fruits,  144 

test  for,  16 
Mineral  water,  definition  of,  6 
Misleading  labels  of  foods,  21 
Mixed  flour,  161 
Model  milking  room,  49 
Model  stalls,  47 
Modern  people  well  fed,  127 
Modified  milk,  35 
Molasses,  manufacture  of,  98 
Mustard,  176 


Mustard,  composition  of,  175 
powdering  of,  176 

New  York  City,  amount  of  milk 
necessary  for,  33 

bacteria  in  milk  sold  in,  53 
New  York  City  milk,  variations  in 

composition  of,  37 
Nitric  acid,  192 
Nitric  oxide,  161 
Nitrogen,  importance  of,  in  foods,  5 

organic,  test  for,  16 
Nutmeg,  176 
Nutmegs,  composition  of,  176 

grinding,  178 
Nutrient  agar-agar,  preparation  of, 

59 
Nutrient  gelatin,  preparation  of,  55 

sterilization  of,  57 
Nutritive  value  of  glucose,  97 
Nuts  and  candy,  adult  ration  of,  102 

food  value  of,  101 

Oil,  coconut,  64 
corn,  91 
cottonseed,  64 
hazelnut,  68 
olive,  66 
peanut,  68 


refining  of,  66 

salad,  66 

sesame,  68 

sunflower  seed,  68 

test  for  cottonseed,  70 
Oil  cake,  91 
Oil  press,  66 
Oils,  60 

determination  of  acidity  of, 

flavor  of,  64 

nutritive  value  of,  64 


INDEX 


207 


Oils,  used  for  food,  68 
Oleic  acid,  62 
Oleomargarine,  74 

manufacture  of,  76 

wholesomeness  of,  75 
Olive  oil,  66 

adulteration  of,  67 

various  grades  of,  67 
Orange  extract,  186 
Organic  matter,  definition  of,  2 
Organic  nitrogen,  test  for,  16 

Paints,  made  from  casein,  40 
Palmitic  acid,  62 
Paprika,  174 

Park,  Dr.  William  H.,  54 
Pasteurization,  131 

advantage  of,  52 
Pasteurized  milk,  50 
Patent  flour,  160 
Peanut  oil,  68 
Peanuts,  composition  of,  114 

food  value  of,  102 
Pectin,  145,  149 

testing  fruits  for,  152 
Pectose,  145 
Pepper,  177 

cayenne,  174 
Pepsin,  digestion  exi)eriment  with, 

16 
Petri  dishes,  55,  196 
Phenolphthalein,  192 

use  of,  in  testing  for  acids,  15 
Phosphate  baking  powder,  167 
Phosphate  powders,  wholesomeness 

of,  168 
Phosphates,  testing  baking  powders 

for,  170 
Phosphoric  acid,  192^ 
Phosphorus  necessary  in  the  diet, 
169 


Pipestem  triangles,  195 
Pipettes,  197 

Plate  cultures  of  bacteria,  58 
Platinum,  197 
Platinum  wire,  195 
Poisonous  aniline  dyes,  123 
Poisonous  constituents  of  foods,  20 
Poisonous  dye,  experiments  with, 

125 
Poisonous  vegetable  colors,  123 
Poisons,  commonly  consumed,  135 

cumulative,  134 

dose  of,  134 
Pomace,  143 
Porcelain  dish,  195 
Porcelain  mortar,  195 
Potassium  nitrate,  83 
Preservation,  advantages  of,  127 

by  alcohol,  132 

by  common  salt,  132 

by  drying,  129 

by  hydrogen  peroxide,  139 

by  smoking,  132 

by  spices,  133 

by  sugar,  133 

by  vinegar,  132 

methods  of,  in  use,  128 

of  decomposed  foods,  138 

of  foods,  127 

proper  use  of  methods  of,  128 
Preservatives,    action  of,    on    bac- 
teria, 137 

chemical,  eflficiency  of,  133 

do  not  sterilize  foods,  139 

experiments  with,  on  human  be- 
ings, 136 

in  milk,  49 

objections  to  use  of,  in  meats,  84 

vs.  cleanliness,  138 
Process  butter,  73 
Protein,  calorific  value  of,  10 


208 


PUKE  FOODS 


Protein,  digestion  of,  16 

excessive  consumption  of,  26 

in  cereals,  159 

present  in  milk,  35 
Protein  content  of  milk,  35 
Proteins,  4 

digestion  of,  5 
Pure  food,  definition  of,  18 
Pure  milk,  production  of,  47 
Pyroligneous  acid,  132 

Rancid  oils,  test  for,  15 
Rapeseed  oil,  68 
Ration,  daily,  23 

of  a  single  food,  cost  of,  29 

of  candy  and  nuts,  102 

of  milk,  36 

standard,  24 

standard,  definition  of,  23 
Rations  for  children,  25 

special,  25,  26 

standard,  23 
Reagents,  189 

Reducing  sugar,  test  for,  15 
Reduction  of  food  value,  21 
Referee  Board  of   United  States 
Department    of    Agriculture, 
136 
Refiners'  sirup,  97 
Refining  of  cane  sugar,  98 
Refining  oil,  66 
Refrigeration,  130 

length  of,  131 

of  meat,  81 
Renovated  or  process  butter,  73 
Resorcin,  171,  192 
Rochelle  salt,  169,  193 
Rye  flour,  162 

Saffron  substitute,  125 
St.-John's-bread,  116 


Salad  oil,  66 

Saliva,  digestion  of  starch  by,  100 

Saltpeter,  83 

Sanitary  conditions  during  drying, 

130 
Saponification,  63 
Savages,  habits  of  eating,  1 
Scarlet  fever  transmitted  by  milk, 

46 
Sesame  oil,  68 
Shakers,  91 
Shellac  varnish,  used  on  chocolate, 

116 
Sifting  machines  for  cocoa,  113 
Silver  nitrate,  193 
Sirup,  concentration  of,  96 

production  of,  from  starch,  92 

purification  of,  94 

refiners',  97 

table,  97 

vacuum  pan  for  concentration  of, 
95 
Sirups,  88 
Skim  milk,  39 

Smoking,  preservation  by,  132 
Soap  making,  69 
Sodium,  metallic,  193 
Sodium  acid  sulphite,  193 
Sodium  carbonate,  193 
Solids  and  mineral  matter  of  milk, 

test  for,  16 
Special  rations,  25,  26 
Spices,  133,  172 

adulteration  of,  177 

exhausted,  178 

importance  of,  in  the  diet,  172 

microscopic  examination  of ,  179 
Standard  ration,  24 

definition  of,  23 
Standard  rations  and  the  cost  of 
food,  23 


INDEX 


209 


Staple  food,  36 
Starch,  88 

action  of  diastase  on,  100 

calorific  value  of,  10 

conversion  of,  into  sugar,  99 

conversion    of,   into    sirup  and 
sugar,  92 

digestion  of,  100 

iodate  paper,  193 

manufacture  of,  91 

natural  products  containing,  89 

necessity  of  cooking,  88 

test  for,  15,  99 

testing  fruits  for,  152 

transformation  of,  3 
Steam  sterilizer,  50 
Stearic  acid,  62 

preparation  of,  69 
Stearin,  61,  66 

preparation  of,  68 
Sterilization,  131 

of  apparatus,  55 

of  culture  medium,  57 
Sterilized  milk,  49 
Substitutes  for  lard,  66 
Substitution  of  foods,  19 
Sucrose,  96,  103 
Sugar,  88 

cane,  manufacture  of,  98 

cane,  refining  of,  98 

function  of,  in  the  diet,  101 

milk,  40 

production  of,  from  starch,  92,  99 

reducing  test  for,  15 

test  for,  by  means  of  Fehling's 
solution,  15 

use  of,  as  a  preservative,  133 
Sugars,  3 

present  in  candy,  103 
Sulphites,  138 

testing  for,  in  meats,  85 


Sulphur,  193 

Sulphur  dioxide,  testing  for,  157 
Sulphuric  acid,  194 
Sulphurous  acid,  83 

injurious,  104 

testing  for,  in  meats,  86 

use  of,  in  candy,  104 

use  of,  in  drying  fruits,  129 
Summer  diet,  fresh  fruits  excellent 

for,  146 
Sunflower-seed  oil,  68 

Table  sirup,  97 
Tartaric  acid,  143 

testing  baking  powders  for,  170 
Tartrate  powders,  wholesomeness 

of,  168 
Test,  for  fatty  acids,  15 

for  mineral  matter,  16 

for  organic  nitrogen,  16 

for  reducing  sugar,  15 

for  solids  and  mineral  matter  of 
milk,  16 

for  starch,  15 
Test  tube,  195 
Theobromine,  112 
Thermometers,  196 
Tonka  bean,  183 
Tonka  extract,  183 
Tripod,  196 
Tuberculosis  transmitted  by  milk, 

46 
Turmeric  paper,  194 

use  of,  in  testing  for  borax,  41 
Typhoid  fever  transmitted  by  milk, 
46 

Unsanitary  meat,  80 

Vacuum  pan,  95 
Valerianic  acid,  145 


210 


PURE  FOODS 


Vanilla  bean,  180 

varieties  of,  182 
Vanilla    extract,    preparation    of, 
182 

pure,  183 
Vanilla  extracts,  composition   of, 

185 
Vanilla  vine,  181 
Vanillin,  182 
Variations  in  composition  of  milk, 

37 
Vegetable  colors,  poisonous,  123 
Vegetable  dyes,  126 
Vegetable  food  colors,  123 
Vegetables,  155 

adulteration  of,  155 

composition  of,  155,  156 

copper  in,  156 

desiccated,  156 

testing  for  starch  in,  99 
Vegetables,  water  in,  155 


Vinegar,  use  of,  as  a  preservative, 
132 

Washington  Monument,  98 
Water,  in  bread,  163 
in  vegetables,  155 
Water  bath,  196 
Week's  food  for  four  adults,  28 
Wheat  flour,  composition  of,  160 
Whole-wheat  flour,  160 
Wholesomeness  of   oleomargarine, 

75 
Wild  mace,  176 
Winter  diet,  preserved  fruits  good 

for,  146 
Wire  gauze,  196 
Witte's  peptone,  194 
Wood  alcohol,  194 

Yeast,  discovery  of,  165 
Yeast  plant,  165 


ANNOUNCEMENTS 


ELEMENTARY  APPLIED  CHEMISTRY 

By  Lewis  B.  Allyn,  State  Normal  School,  Westfield,  Mass. 


izmo,  cloth,  127  pages,  illustrated,  60  cents 


This  book  offers  practical  applications  of  chemistry  to  pres- 
ent-day civic  and  industrial  problems.  The  course  is  essentially 
that  conducted  by  the  author  in  the  Westfield  State  Normal 
School,  where  a  pure-food  campaign  has  been  made  one  of  the 
objects  of  the  course.  The  widespread  results  shown  in  the 
almost  complete  elimination  of  the  sale  of  impure  foods  in 
the  city  of  Westfield  are  matters  of  national  knowledge. 

Besides  the  work  with  food  products,  the  book  includes 
exercises  with  water,  textile  fabrics,  drugs,  soils,  and  similar 
materials.  It  gives  a  particularly  complete  analysis  of  each 
subject  and  brings  out  clearly  the  practical  relation  which 
chemistry  bears  to  everyday  matters.  The  order  of  presen- 
tation differs  radically  from  that  of  the  usual  textbook  in 
chemistry,  the  common  elements,  bases,  and  radicals  being 
taken  up  as  they  naturally  occur. 

For  supplementary  use  with  any  regular  textbook  "  Elemen- 
tary Applied  Chemistry  "  is  invaluable.  Teachers  of  domestic 
science  will  find  the  chapter  on  food  values  most  important, 
while  for  boards  of  health,  inspectors  of  milk,  and  all  those  inter- 
ested in  the  pure-food  problem,  the  book  has  a  special  function 
in  its  valuable  information  and  tests  relating  to  their  work. 

151 

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BACTERIA,    YEASTS,    AND 
MOLDS  IN  THE   HOME 

By  H.  W.  CONN 

Professor  of  Biology  in  Wesleyan  University.    1 2mo,  cloth, 
293  pages,  illustrated 


THE  book  contains  an  important  summary  of  the  facts  which 
have  rapidly  accumulated  in  recent  years  concerning  the 
relation  of  microorganisms  to  all  matters  connected  with 
the  home.  The  work  is  a  popular  and  not  a  scientific  discussion, 
free  from  many  technical  terms,  and  admirably  adapted  to  the 
needs  of  the 'housewife,  the  student  of  domestic  science,  and  all 
others  interested  in  home  economics. 

Molds,  which  are  the  cause  of  mildew,  the  spoiling  of  many 
foods,  and  the  decay  of  fruits  ;  yeasts,  which  are  the  foundation 
of  fermentation  in  the  raising  of  bread  ;  and  bacteria,  which  cause 
food  to  spoil,  meat  to  decay,  and  contagious  diseases  to  spread,  — 
all  these  phenomena  which  are  of  the  most  vital  importance  are 
presented  in  an  interesting  and  helpful  manner.  The  author 
explains  the  various  actions  of  bacteria,  and  points  out  the  sources 
of  trouble  and  the  principles  which  underlie  the  methods  to  be 
adopted  for  avoiding  their  effects.  Special  attention  is  paid  to 
the  problems  of  food  preservation  and  to  the  practical  methods 
which  can  be  used  in  the  home  for  preventing  the  distribution 
of  contagious  diseases. 

To  render  the  work  more  useful  for  classes  in  domestic  science 
there  is  added  an  appendix  containing  directions  for  a  series  of 
simple  experiments  which  will  give  to  the  student  a  practical 
knowledge  of  the  most  important  properties  of  microorganisms. 

"—  ~ 

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AN  ELEMENTARY  STUDY   OF 
CHEMISTRY 

By  WILLIAM  McPHERSON,  Professor  of  Chemistry  in  Ohio  State  University, 
and  WILLIAM  E.  HENDERSON,  Associate  Professor  of  Chemistry  in 
Ohio  State  University. 

i2mo,   cloth,  434  pages,   illustrated,   ^1.25 


THIS  book  is  the  outgrowth  of  many  years  of  experience  in 
the  teaching  of  elementary  chemistry.  In  its  preparation 
the  authors  have  steadfastly  kept  in  mind  the  limitations 
of  the  student  to  whom  chemistry  is  a  new  science.  They  have 
endeavored  to  present  the  subject  in  a  clear,  well-graded  way, 
passing  in  a  natural  and  logical  manner  from  principles  which  are 
readily  understood  to  those  which  are  more  difficult  to  grasp. 
The  language  is  simple  and  as  free  as  possible  from  unusual  and 
technical  phrases.  Those  which  are  unavoidable  are  carefully 
defined.  The  outline  is  made  very  plain,  and  the  paragraphing 
is  designed  to  be  of  real  assistance  to  the  student  in  his  reading. 

The  book  is  in  no  way  radical,  either  in  the  subject-matter 
selected  or  in  the  method  of  treatment.  At  the  same  time  it  is  in 
thorough  harmony  with  the  most  recent  developments  in  chem- 
istry, both  in  respect  to  theory  and  discovery.  Great  care  has 
been  taken  in  the  theoretical  portions  to  make  the  treatment  simple 
and  well  within  the  reach  of  the  ability  of  an  elementary  student. 
The  most  recent  discoveries  have  been  touched  upon  where  they 
come  within  the  scope  of  an  elementary  text.  Especial  attention 
has  been  given  to  the  practical  applications  of  chemistry,  and  to 
the  description  of  the  manufacturing  processes  in  use  at  the 
present  time. 

EXERCISES     IN     CHEMISTRY.       By    William    McPherson    and 
William    E.    Henderson.  40  cents.     In  Biflex  Binder,  60  cents, 

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TEXTBOOKS  IN 
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PHYSICS 

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Gage  :  Physical  Experiments 35 

Gage  :  Physical  Laboratory  Manual  and  Notebook 35 

Gage  :  Principles  of  Physics  (Revised  by  Goodspeed)  ....  1.50 
Hastings  and  Beach  :  Textbook  of  General  Physics  .     .     .    *.     .     2.75 

Higgins :  Lessons  in  Physics 90 

Higgins  :  Simple  Experiments  in  Physics 35 

Hill:  Essentials  of  Physics i.io 

Ives:  Experiments  in  Physics 50 

Miller:  Laboratory  Physics 2.00 

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Millikan  and  Gale :  First  Course  in  Physics  (Rev.  Ed.)  .     .     .     .     1.25 

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CHEMISTRY 

Allyn  :  Elementary  Applied  Chemistry 60 

Dennis  and  Whittelsey:  Qualitative  Analysis  (Rev.  Ed.)  .  .  .  i.oo 
McGregory:  Qualitative  Chemical  Analysis  (Rev.  Ed.)  ....  i. 00 
McPherson  and  Henderson  :  Course  in  General  Chemistry  .  .  2.25 
McPherson  and  Henderson:  Elementary  Study  of  Chemistry      .     1.25 

McPherson  and  Henderson  r  Exercises  in  Chemistry 40 

Moore  :  Logarithmic  Reduction  Tables [/« ^ress] 

Morse  :  Exercises  in  Quantitative  Chemistry 2.00 

Olsen :  Pure  Foods :  Their  Adulteration,  Nutritive  Value,  and  Cost  .80 
Ostwald  and  Morse  :  Elementary  Modern  Chemistry  ....  i. 00 
Sellers :  Treatise  on  Qualitative  Analysis  (Rev.  Ed.)       ....     i. 00 

Thorp:  Inorganic  Chemical  Preparations      •     •     •. ^-5° 

linger:  Review  Questions  and  Problems  in  Chemistry 50 

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